Constantly turning off, should I replace logic board?

So I’m asking for a bit of advice here. I have this MacBook 13” late 2013 A1502 serial number C02LXB5FFGYY.

Should I try to replace the logic board or should I do more investigation?

it might have had some water or juice spilled on it, but no one in the family recalls anything, but the space key is “sticky”/“slow to rise”, and mark is noted on the logic board after a small strip of running liquid, where some tiny weldings on the logic board is corroded just a bit. No sign of liquid anywhere else.

The problem is that it suddently just shuts of at random moments, maybe after 10 min or 3 hours, so it is kinda unusable. There is no warning in OS X or no error message on screen, it just goes dark/turns off and then immediately after then fan is blowing wild.

It also happens with the power cable plugged in.

I did all the reset PRAM and the other thing. Did a battery test and a harddrive test, also did the apple error test from boot, also successfully did a reinstall of OS X without a shutdown happened.

I monitored the temperature with a software and nothing went above 90 degrees Celsius as I recall.

I read the OSX logs on the time interval of a blackout and no error was seen.

So I bought a tool kit from ifixit and took the logic board out, cleaned the spilled area with a soft toothbrush and some isopropyl alcohol (99% or something like that), dried it, new paste on the CPU etc as the guide, put it back and I still did the same sudden blackout!!

So should I just buy a new used logic board and replace it? Or do anyone recommend me doing anything else? Tjek some other hardware?

I actually have a 10L ultrasonic cleaner (doing motorcycle rebuild).

hope someone can help me!! :)

kinds regards, Mathias, Denmark