mine worked just fine for about 1day.
suddenly it stopped : screen is blanked after power on. presumably it stopped after some rapid buttons pushing, possibly power button too.
the battery is fully charged. the soldering is imho decently good. battery plugin/plugout does not difference. brightness is working, no sound whatsover. sdcard seems ok too.
to me it looks like the bootloader is not executing.
how do i troubleshoot from here? anything i can do with rs232?