Try lowering the Bits per second to or 57600 , and match this setting inside your flashing software. 3. The "Power Cycle" Timing

The STB wasn't powered on at the exact moment the software expected it.

The Universal Asynchronous Receiver-Transmitter (UART) is the hardware component responsible for serial communication. "Receive Full" indicates that the STB's data buffer is jammed. It cannot process the incoming bits fast enough, or the data is arriving "corrupted," causing the buffer to hang. Primary Causes