Chosen Solution
While I was using my mac, it shut down suddenly and since then I am unable to turn it on. When I pressed the power key the only thing I can hear is both fan running at full speed. Even if I open the lid (without pressing the power key) the fan starts running at full speed with no sign of powering on. What might be the possible solution?
Unplug and remove battery. Wait about 20-30minutes and retry powering it up. It may work. As to why, I can’t say. This has happened to me and I left it off for a day and magically it rebooted
At this point you need to find someone with the needed skills and tools to check your system out. If you can get your system to startup again see if you can get the onboard diagnostics to run pressing the D key when you restart your system, If you get an error let us know. Reference: Mac startup key combinations I would also install this gem of an app! CoconutBattery take a snapshot of the apps main window and post it here for us to see Adding images to an existing question
