It all started when the Digma E629 eBook had been sitting unused for quite a long time, and when I finally decided to charge it and use it again — it refused to turn on. At that moment the device was almost 10 years old, so it was not surprising that the first disassembly immediately revealed a completely discharged Li-Ion battery (3.7V 306573, 1500mAh). Fortunately, this is a common form factor, so I easily found and ordered a replacement.
However, after replacing it… the problem remained. The display did not refresh, although the device was detected via USB and the battery was charging normally. I connected to the UART port (standard speed 115200) and started digging deeper.
