I own a RK3328-CC Renegade, not the elite, but that board has a problem booting with certain displays attached. Maybe the Elite has the same issue?
Could you try disconnecting HDMI during boot and then plug it in afterwards? Watch the LEDs to see when it’s booted.
If that still doesn’t work, looking at UART is your next move. Pins are listed here, with the elite at the end of the list:
The baudrate is 1.5Mbps, so make sure your USB-serial cable supports that. Not all of them do.
Good luck