Hi @paxonator ,
Disconnect the power from the TV and restore all the connections between the boards, then disconnect the mainboard from the power board and then reconnect the power to the TV.
''The backlights should turn on full intensity and stay on.''
If they blink or don’t stay on then there is a problem either with the power board or the backlights
Check the voltage at the LED power connector on the power board. If the backlights aren’t on and it is >230V DC then there is a problem between the power board and/or in the LED array. If it is <50VDC it is in the power board. Test between the connector and earth for the voltage
If the backlights stay on then there may be a problem in the mainboard or the power board.