If you still see "UART receive" after trying all 6 steps, your near the processor may be physically damaged or missing. In that case, you need a hardware serial TTL adapter (CH340) to manually send the update command.
: This suggests an issue during the boot process, specifically related to the boot ROM (Read-Only Memory). The boot ROM is a small memory that contains the initial boot code for the device. If you still see "UART receive" after trying
In simple terms:
(If you don’t know the SoC, identify it from PCB markings, vendor model, or BootROM output.) identify it from PCB markings