No Backlight on iMac. Next Steps?

Hi Everyone! I picked up a 2012 IMac A1418 EMC 2544.

The LCD Panel works, but there is no backlight. I am able to use a flashlight and I can see everything and it functions perfectly. AHT said no issues. The computer also can connect to an external display and everything is perfect. My question is, what are the next steps in diagnosing the issue? From my research, I am pretty sure I will have to replace the logic board. Is there anything I can/should do before doing a full logic board replacement?

Thank you in advance!