battery not charging but MacBook runs fine when plugged in

I damaged my keyboard some weeks ago when cleaning (foolishly used a wet wipe rather than an alcohol wipe and damaged some keys). I used the computer for weeks with an external keyboard and during that time the battery and charging circuit worked fine. I then completed an upper case replacement and got the internal keyboard working fine. But now the MagSafe light is very dim and the battery will no longer charge. The computer works fine when plugged into the power adaptor. Under system report the battery is shown as present (showing cycle count an such) and the AC charge is shown as connected. But battery charging is listed as "no"

I have tried resetting the SMC following the recommended procedure and also tried resetting it by disconnecting the battery for some time and holding down the power button for 10 seconds. But none of this worked.

I'm guessing I damaged the MagSafe DC-in board when replacing the upper case (although there were no obvious problems during that repair). But wondered if there is any other simple debugging I can do before I make that second repair. Don't want to miss some easy fix and don't want to bother with the DC-in board replacement if there is a larger problem. For now the MacBook is working find as a desktop :)