Release Pandora Recovery SD-Card image

EvilDragon

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Finally I found the time to create a Pandora Recovery and Testing card image.
If your Pandora appears to be dead, you might be able to get it back into a working state with this.

You can download it here


Here are the instructions:

Pandora Recovery and Testing Card

The included image file can help you to recover and / or test your Pandora.
It can even be used if the Pandora bootloader is completely broken and the unit doesn't show any signs of life anymore.

Here's how to use it.

1. Create the SD Card using the included image

You need an SD card which is at least 512MB of size.
Use your favourite tool to flash the included pnd_recovery.img on your SD Card.

Some examples of tools that can do that:

Balena Etcher: https://www.balena.io/etcher/
Win32 Disk Imager: https://sourceforge.net/projects/win32diskimager/

Of course, if you're a more experienced user, you can also simply use dd command to do so:

dd if=pnd_recovery.img of=/dev/<yourdevice> bs=4M

Once the image is flashed on the SD Card, you can force-boot it on your Pandora.


2. Prepare the Pandora to run the SD Card

Basically, there are two reasons that your Pandora can behave like it's dead:

a) The bootloader is broken (can be fixed with this SD Card)
b) The battery is totally flat.

In both cases, the Pandora will not show any signs of life. Not a single LED will light up.
So before trying to recover the bootloader with your SD Card, make sure the battery is fine.

It's a good idea to put in the battery into the Pandora first and then connect the charger for at least 2 hours.
If it doesn't come back to life, then the battery should at leave have received enough charge to boot the recovery card.

Note: Do NOT use the Mini USB port to charge it. If the battery is flat, only the AC Power connector does charge it.
You can also check the battery using a multimeter to make sure it has a voltage of at least 3.2V or higher.

Once you are sure the battery is fine and the Pandora still is dead, continue with the next step.


3. Booting the recovery SD Card

a) Put the recovery card into the left SD Card slot.
b) Press and hold both the Pandora-Button (the button with the Pandora logo on it) and the START-Button on your Pandora at the same time and keep them pressed.
c) Flick the power switch to the right (switching the unit off)
d) After about 2 - 3 seconds, it should come back to life and start booting. You can let go of the Pandora- and START button now. It will boot into a testing / recovery menu.


4. The testing and recovery menu

The SD Card offers various options and tests.
If you just want to reflash the OS, simply choose "0" and press ENTER. It will then reflash the bootloader and OS and your Pandora should boot properly again after it's done.

Here is a brief explanation of the tests:
  1. LED-Test: This test switches on all LEDs on the Pandora. Please note that the LED for the second SD Card slot will only light up if there's a card in that slot.
  2. SD 1 / 2 Write-Protection-Test: This tests the write-protection detection of the SD Cards. It will fail in most Pandoras, so don't worry.
  3. USB OTG / Host / SD 2-Combo-Test: This test will make sure both of your USB-Ports and the second SD-Card-slot is working.
    To run the test, you need to plug in a MiniUSB > USB-Cable into your Pandora. So basically, connect the big USB port with the Mini USB-Port.
    It should be plugged in before you start the Pandora. Also, it needs to have a FAT32-formatted SD Card in the second slot.
  4. SD Slot 2 Test: To only test the second SD Card slot, put a FAT32-formatted SD Card into the slot and run the test.
  5. USB-Stick-Test: Same as the SD Slot 2 test, just with a USB Stick,
  6. TV-Out-Test: This simply enables the TV Out. You should see the flasher-menu on your TV afterwards.
  7. WiFi Test: To run the Wifi-Test, you need to set up an unprotected access-point with the ESSID PND_TEST. The Pandora will then try to connect to it.
  8. Flash the Battery Chip: This reflashes the calibration data onto the battery chip. Only do that if the Pandora does totally wrong battery readings.
  9. Input-Tester: Here you can test all inputs (keys, nubs, touchscreen) of your Pandora. To exit, press L+R+Pandora.
  10. Bluetooth-Tester: This enables the bluetooth chip. It's just a quick functional test.
  11. Quit the test and reflash the system: This will completely wipe your internal storage and reflash the bootloader, the kernel and the OS.
    This basically resets the Pandora to factory settings.
  12. Quit the test and save the log to the SD-Card: This will end all tests and save detailed results onto the SD Card. It's normal that it says "Update failed", so don't worry about that.

That's it - and good luck in getting your Pandora back to work!
 

HelenF

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Thanks for setting this up ED!

Wow, the magic key is Pandora Button + Start? I don't think that was any of the ones people told me last time...

I thought I would test the SD card on my working CC Pandora first. When things are working, is it possible to see whether the SD card MLO boot worked or not? Because as I understand it, if the ROM bootloader can't see the MLO file, it loads Stage 2 from NAND anyway, which then goes to autoboot.txt on the SD card.

However, I seem to have partially broken the bootloader on the NAND at some point while messing around here. The internal OS still boots; but if I start the Pandora while holding the right shoulder, or if I start it with any card having autoboot.txt in the left slot, it hangs with a blank screen, with just the backlight and the rightmost LED on. If I start it while holding the right shoulder with no SD cards in the slots, I should still get a menu, right?

So, now it seems that the SD card MLO boot isn't working. Should I try a different SD card? I vaguely remember hearing that smaller ones are more likely to work.
 

PowerGod

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Basically, there are two reasons that your Pandora can behave like it's dead:

a) The bootloader is broken (can be fixed with this SD Card)
b) The battery is totally flat.
I suppose mine was the c) case then :'(
 

HelenF

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I thought my symptoms above might also point to a problem with the SD card slot, but I did some SD card testing from the internal OS, and that still seems to be working.
 

trix

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Note: Do NOT use the Mini USB port to charge it. If the battery is flat, only the AC Power connector does charge it.
I just wanted to point out, the AC power plug for my Pandora hasn't worked in years, and I can only use mini USB to charge it.

I have had the Pandora completely 100% super dead and unresponsive, and when I plug in the mini USB port to charge it, nothing happens. However, if I leave it plugged in overnight, by morning it's awake and charging. It takes a really long time, but the mini USB port can absolutely be used to recover a completely dead Pandora battery. This is an original CC first batch Pandora. I do not know if other versions work this way.
 
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HelenF

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I borrowed a 2GB SD card but it doesn't seem to have made any difference.
 

HelenF

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@EvilDragon Thanks for your work so far!

a) Put the recovery card into the left SD Card slot.
b) Press and hold both the Pandora-Button (the button with the Pandora logo on it) and the START-Button on your Pandora at the same time and keep them pressed.
c) Flick the power switch to the right (switching the unit off)
d) After about 2 - 3 seconds, it should come back to life and start booting. You can let go of the Pandora- and START button now. It will boot into a testing / recovery menu.
The above doesn't work on my CC unit. (As I noted earlier, it will appear to work if there's a good bootloader on the NAND.) The following, however, did work:

a) Remove the battery.
b) Put the recovery card into the left SD Card slot.
c) Press and hold both the Pandora-Button (the button with the Pandora logo on it) and the START-Button on your Pandora at the same time and keep them pressed. Or it might actually just be START. (I over-eagerly reflashed when I had the chance, so can't check now without finding out how to build the bootloader, or killing my newly-flashed bootloader on purpose.)
d) Insert the battery and wait a few seconds. If it booted, you can release the button(s) and put the battery cover back on.

It seems my GHz unit has a different problem, so I guess I'd need to send it in :(

----

Feature requests for the rescue card:

1) Program the rescue card bootloader to do something visibly different from the one on the NAND so we have a better idea what's going on when trying to boot it.
2) An option to only reflash the bootloader. (I tried force rebooting while it said "calculating checksum", and maybe that would have worked if something on the NAND wasn't corrupted already, but a safe option would be great.)
 

EvilDragon

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The START button is what forces the system to boot off the SD Card.
The Pandora and Power Switch button is just used to RESET the unit.

If you already have a battery in, it could be that the unit is already on (though with a broken bootloader, it behaves like it's switched off).
So pressing START alone wouldn't work - that's why I'm mentioning the PANDORA + Power Switch method here - it resets the unit, so it reacts again on the force boot button.

And yes, if you only want to flash the bootloader, it's safe to switch off the unit while it's doing the "calculating checksum" for the OS.
 

HelenF

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The START button is what forces the system to boot off the SD Card.
The Pandora and Power Switch button is just used to RESET the unit.
OK, thanks for clarifying that!

If you already have a battery in, it could be that the unit is already on (though with a broken bootloader, it behaves like it's switched off).
So pressing START alone wouldn't work - that's why I'm mentioning the PANDORA + Power Switch method here - it resets the unit, so it reacts again on the force boot button.
I tried a bunch of times and that definitely didn't work for me, and then taking the battery out did work. (PANDORA + Power Switch does normally restart the unit, so no hardware problems there.)
...
And it just occurred to me that maybe I had some kind of power issue, and taking the battery out fixed it. But I'm 99% sure I took the battery out in the middle of all my CC booting attempts, to try in the GHz unit...

And yes, if you only want to flash the bootloader, it's safe to switch off the unit while it's doing the "calculating checksum" for the OS.
It flashes the kernels before that. I thought it said it hadn't done anything at that step because it was already done, but maybe didn't read it properly. I guess if it flashed a different kernel and stopped before the main OS, that might result in a non-bootable system.
 
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levi

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If it has a functioning kernel but a broken filesystem on an x86 linux at least then you'll at least get some messages from the bootloader, but I don't have a functioning Pandora to hand to compare.
 

EvilDragon

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If it has a functioning kernel but a broken filesystem on an x86 linux at least then you'll at least get some messages from the bootloader, but I don't have a functioning Pandora to hand to compare.
The bootloader on the Pandora consists of two parts: The MLO which configures the system and then loads U-Boot. Both have to be intact to make the Pandora at least do something. If the MLO is intact but U-Boot isn't, you will see no signs of life (except that it will drain your battery over time).

When the MLO and U-Boot are both intact, the LEDs should go on and the Pandora logo will appear on screen. If it doesn't find a kernel, a bootmenu will pop up (the same as when you hold R while switching on).

If it finds the kernel, it will boot that - and yes, then you will see various boot messages if something goes wrong.

You can switch from the splash screen to the bootlog with START + DPad left / right.

If the system boots but some things like the touchscreen don't work, you have a different kernel version than OS version.
 

HelenF

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  • My CC Pandora would boot the OS from NAND, but would hang when it tried to show the R-shoulder boot menu or boot an SD card having autoboot.txt. I suspected a slight corruption in u-boot.
  • The suggested way of booting the recovery card didn't work even after an orderly shutdown. Eventually, I booted it by inserting the battery while holding the buttons.
  • I over-hastily started a reflash rather than doing more testing.
  • I interruped the reflash at "calculating checksum". U-boot on the NAND then worked again (could show the R-shoulder boot menu and boot SD cards) but booting the OS from NAND stopped at a black screen with some errors. I over-hastily didn't take a note of them, just thought "oh well I shouldn't have interrupted it", and did a full reflash. Then everything was back to normal.
 
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