Take it apart and re-seat the sound-card board that connects the HDD. When you reconnect it make very sure that the white cable with something like 6-wires is connected securely at both ends because that powers the hard drive on that model.
That happened to me a while ago.

Hopefully that's all it is?
While you're in there it's a good idea to check for corrosion and remove the standby battery under the keyboard and throw it in the bin. The smaller RTC battery is probably also leaking and should be replaced.

no corrosion except on the connectors for each batteries, i tried and checked everything and no change. i already chucked both dead batteries in the trash