Ross P, I can’t see anything on the boards that concerns me much. Have you tried measuring the output voltage of the inverter board, that drives the backlight? Try measuring the output and let us know what the voltages are as that can help in diagnosing.
There are two main ways of testing the backlight:
# Test the output of the inverter board
# Apply the correct power to the backlight externally
2 requires a power supply that can provide the correct voltages at the appropriate amperage. Should light up the backlight if it’s working. There are some backlight tester thing-a-ma-jiggies / do-hickey’s on Amazon, though I’ve never used them myself.