MacBook air early 2017 won't go on after power down

Hi All

i have this macbook air from early 2017 and this is very weird.

One day it just did not power on again, so i opened it up.

When i unplug the battery and plug in the charger it works.

it restarts completely and all is ok. ( battery has been replaced, thougt this would help but no :( )

When i plug the battery back in also nothing happens. I can work on the laptop and everything is fine.

What does concern me is that when i power down the laptop it won't turn on again unless i open it up unplug the battery and put in the power kabel again.

He also somethimes just goes out when having a full or nearly full battery

Resarting is no problem once it's on it's on but when you turn him of he is gone.

Has any of you had this problem before?

And an even better question is this fixable?

Thank you all

Kind regards

Cathy