MacBook not powering on, no light on charger

Hi!

I’m trying to help my friend with his Macbook air. It seemed completely dead and has been so for about a year, maybe more. No water damage. So the first thing I did was to put the charger in, and from out of the blue it booted up! I charged up the battery and thought that everything was solved, miraculously. A week after I just wanted to see if it still worked - and it was completely dead. No light from the charger, no reaction to anything. Tried to reset SMC, but nothing.

I read in another question here that unplugging the battery could maybe fix it, so about 1 hour I tried to boot the Macbook with the battery unplugged. The Magsafe was first green, then after a couple of seconds it turned red/orange and the booting chime started. But just before it was about to boot the charger turned green, the computer turned off and then finally the charger went black.

That’s pretty much it. Would really appreciate your inputs on this :)

Thanks!

Anyone that has any ideas?