: Using an incorrect COM port in the flashing software or having outdated/corrupt drivers for the RS232/USB-to-TTL adapter.

Since the box is asking for a UART connection, you can often bypass the physical serial port by using a USB-to-USB Male-to-Male cable Get the Firmware

: Use a high-quality USB Male-to-Male cable. Avoid excessively long cables which can cause signal degradation.

Unplug your USB adapter, swap the RX and TX wires, open your terminal at 115200 baud, and try again. Nine times out of ten, that single action solves "please check stb uart receive."

This specific error message () is typically associated with Android TV Boxes and Amlogic chipset-based devices (often used by brands like X96, Tanix, Nexbox, or generic OEM boxes).