Reply by dhazelton

I don’t know how you could control the depth of the cut with a forstner bit in a hand held drill but you can certainly try. Can you pop the back off and cut the shelves out and clean out the dadoes with a small chisel? Then you could make new shelves and would only have to bore new holes in the one by bottom. Or else you could through drill new shelves with right diameter hole and glue them on top of the shelves that are already there. If this is something she payed you for you may have to suck it up and make another carcass as the error was yours. On the bright side, it doesn’t look too complicated.