My MacBook died for 8 months and then turned on by itself

My laptop stopped working one day and refused to turn on by all means. I tried all the solutions that worked for other people with the same problem and nothing worked. There was no fan working so not only wasn’'t the display working, but also the laptop itself. When I tried to plug it in, the light inidcated to me that it was charging though.

Nothing worked for 8 months and one day, I don’t know what made me try and turn it on again, it worked. It works as if nothing happens, but I am afraid it won’t start up again if I shut it down at some point.

What could the problem be? The battery? Some bad contacts? What should I do to prevent it from not working again and hw can I find out what the problem was if it works completly fine now?