The TX (Transmit) and RX (Receive) pins on your UART adapter or the STB board are not making solid contact.
"Not again," Elias muttered, rubbing his eyes. In the world of embedded systems, this was the digital equivalent of a heart stopping on the operating table. The Bootrom—the most primal level of the device's brain—was shouting into the void, waiting for a signal that never came. Bootrom Error Wait For Get Please Check Stb Uart Receive
The Transmit (TX) wire from the USB-to-UART adapter must connect to the Receive (RX) pin on the STB, and vice versa. The TX (Transmit) and RX (Receive) pins on