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Power button stopped working a while ago, so the computer was never turned off until it was on battery power and died. Now it will not turn on when I press it, i’ve tested both memory chips and the HD still works fine. I don’t know if this is important, but in complete silence I noticed that if I press the button I hear an ever so slight ticking noise, just a little faster than a clock (not from the HD I think) and a very very soft hum. Any ideas?

This is a common problem. You need to replace the top case/keyboard.

If the battery completely drains it will not start with the battery in. Let it charge for 30 minutes. It sounds like you need to reconnect your keyboard to logic board cable. If this becomes disconnected the unit will not start or stop till the battery dies. here’s how to get to it: MacBook Core 2 Duo Upper Case Replacement

Another option, if your handy with a screwdriver, is to try the internal power button, which actually nothing more than to points on the MLB near the fan, Depending on Generation, it will be marked pwr btn, or with the power logo. Short them with a small screw driver, see if the machine turns on. If it does power on from there its almost always the top case that needs replaced, If it does not, then you are looking a deeper issue on the logic board itself. Also, Does the laptop have a liquid spill in its history, Liquid is the most common killer of top cases, and if thats at fault, your issues will most likely go deeper into the unit. Mark Grummell Indianapolis, IN