: Without a shared ground reference between the USB-to-UART adapter and the STB board, serial data becomes corrupted.
The error explicitly states "check stb UART receive" . You must have a physical UART-to-USB adapter (PL2303, CP2102, or FTDI). : Without a shared ground reference between the
Insufficient power during a boot cycle can occasionally cause the BootROM to hang in this diagnostic state. Potential Solutions Hardware Reset: Unplug the power cable from the STB. Data bits to 8
Set your serial connection speed to 115200 Baud, Data bits to 8 , Stop bits to 1 , and Parity to None . Stop bits to 1