From Google’s Android TV GMS (Google Mobile Services) hardware compliance and public Amlogic bootROM documentation:
: 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. From Google’s Android TV GMS (Google Mobile Services)
Do you have the of your set-top box so I can look for the specific factory firmware or recovery tool? : A failed over-the-air (OTA) update can break
: A failed over-the-air (OTA) update can break the "Chain of Trust," leaving the device unable to verify its next boot stage. Android Open Source Project Potential Fixes Reflash Original Firmware From Google’s Android TV GMS (Google Mobile Services)
: The device is in a listening state, waiting for the computer to send the 0x7F (Get) command to initiate data transfer.