It can be a charging problem, I fixed some of this computers, and the fact is that the charging port is secured by small ring of plastic and it does not support heavy use.
The charging port (DC Jack ), has a third connection on the center that communicate charger with motherboard, if something happen with that communication you still can see your computer powering on but it never will charge until the computer has a full connection.
Well, Just try with a new charging port…
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