Hi,
I wanted to see if my unit does power draining as well while switched off, so here is the result.
I used cat /sys/class/power_supply/pyra-battery to show the charge.
Result: Before shutting down: 4063000 After two hours: 4021000 Another 5 hours later: 4028000
So at first it looked like it loses a bit of charge, however, five hours later, the charge was a big higher again.
I guess this is because the battery is still warm before I shut it down the first time, then cooling off changed the voltage a bit and that's it.
I'll also do the test with a multimeter and a day waiting time.