MacBook Pro Retina E2015 A1502 green light, wont turn on

Hey Community,

I have a MacBook Pro 13” Retina 2015 (A1502).

The issue is it was 4 days in Standby mode and then it didnt turn on anymore.

First:

If I plugged inn the magsafe, nothing happened and the magsafe light was off. Then I plugged off the battery and tried it again and it didnt worked either.

I used the magsafe with another macbook and the charger worked. After this I tried it again on the macbook with the issue and it worked with battery plugged off.

If I plug in the battery and reconnect the magsafe, the magsafe light will be off. Then I cleaned the I/O board, because the liquid indicator was green, and now the magsafe light is green for most of the time.

If I charge another MacBook with the magsafe and the light is orange and i use in the next step the magsafe on the MacBook with the issue, it will be orange aswell. So it keeps the light color.

Second:

Now the magsafe is green most of the time but the macbook still dont turn on. I tried SMC, PRAM and NVRAM reset, it didnt turn on either. Aswell I tried to pull off the battery and plug in the magsafe and use the power button to start it, but it didnt work either.

Now I am not sure if its the powerbutton itself. The battery looks fine.

Thanks for any recommendation.

Sincerely