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Do you mean something gets burnt in the DCIN board?
Are you using original 60/85W Magsafe 2 charger?
The machine works good with battery, but doesn't start with charger alone?
I can only think you don't use original Magsafe 2 charger.
Fake magsafe charger delivers max voltage from the first moment; that could be 15-18V.
Original charger delivers only 3V in the first moment; nominal voltage appears after it correctly detected the board.