Chosen Solution
I have tried the preferences etc, but cant get the backlight to work on the keyboard. Apple recently did a logic board repair, could that have anything to do with it?
Yes, they could have plugged it wrong or not at all. Find the iFixit guide for your model, that explains how to disassemble the keyboard. Just don’t remove anything. Only look for the backlight flat cable and plug it in or reseat it. EDIT: Step 27 of this guide. Better yet, take it to the Apple Store where they fixed your laptop and have them correct the issue, as trying to repair it yourself may damage it and/or void the warranty.
Unsecured the latch and pull the circled connector cable (as shown in pic) out gently and insert back in. Secure the latch. If didn’t work, ask Apple to replace it. They are obliged to if it was their LB replacement job. Hope this helps.
