I reset the device, but it still wouldn't power on. When I tried to turn it on while connected to a data cable, the screen remained black and couldn't access the system. When using the battery to power it on directly, the screen would flash briefly and then go black. I thought the problem was with the battery, so I disassembled the device, removed the battery, and replaced it with a new one. However, the device still couldn't enter the system after the replacement. I measured the battery voltage, and it was normal, so I couldn't resolve the issue. Some people told me that the problem was a system crash and that the only solution was to reflash the firmware. Eventually, I found a repair shop. After inspection, they found that the issue causing the power-on/off failure was a damaged remote control Type-C USB connector - horizontal type - 24pin. The inspection photos are shown below, and the device returned to normal after the connector was replaced.
