Hi, I received back the CPU board (C41) with IM8G RAM chips on Friday and had now some minutes to look into it.
GC did X-Ray and found several short circuits under the OMAP5432.
Then we X-rayed the second CPU-Board that I had reworked (C35) myself and it showed the same effect of shorts of BGA balls in the middle of the OMAP5.
Here I know from intermediate tests that these shorts did not exists before starting rework and not even after unsoldering the DRAM chips. It clearly happened on the second reflow step when soldering new DRAM chips.
So it appears that rework (doing multiple reflow steps) risks that these shorts appear and the OMAP (very expensive thing) has to be replaced as well.
Maybe excessive flux is flowing under the OMAP5 and making this trouble.
I did only do a very quick boot test and it appears as if the 4GB board boots well with the 2GB U-Boot.
With 4GB U-Boot it prints two lines and then hangs. But I do not exactly know which MLO with which EMIF settings I have on this SD card so a full test with reliable results needs more time.
BR, Nikolaus