Yamaha CVP-98 dead low keys

I was gifted this piano, the low keys do nothing, all other stuff works fine…Looks like someone dropped a cup of coffee on the low key side…I cleaned the board but didn’t work…ordered a new board and still nothing…I sure would like to get it working…10 grand kids…please any help would be great…thanks too…

Exactly which keys are not working !?

Check the connecting ribbon cables for bent pins. Did you replace all the MK boards or just the lower one?