So this is kind of old news for the older Macbook Pro owners but I think its interesting:
It all started with my trackpad on my laptop being very sensitive, and eventually clicking randomly when i touched anywhere around the trackpad.
Then I found my computer turning off randomly when I didn’t have the Macbook plugged in.
A short time later I found my battery was the problem and it had been swelling underneath and pushing up against the interior of the laptop.
If you have any of these symptoms. This is one probable cause. You will need a new battery regardless, but it happened to me, so I thought I should spare you the question marks.