check for shorting on plug? is it an OEM plug? pin alignment proper? an OEM charger? what were the symptoms before it went dark? check for heat damage from the possible shorting at the plug and the board, if it has gotten that hot it may have re-soldered its own connections
together- check for any abnormal solder flow anywhere near the heat source.
is the pwr button stuck in the depressed pos?
these are just off the top of the ole noggen, good luck. and remember to use your heat-sinks.