Nintendo Switch won’t turn on after shutdown

Hi all, really hoping that someone can help me! I bought a faulty Switch online and after opening realised that it had succumb to some water damage, however after cleaning up the board and re assembly the console started to charge with the symbol showing, result! The console went through that slow charge cycle and the kicked in to fast charge with the Switch booting to the home menu with everything working, games, SD, everything.
But here’s where it gets weird, whenever I shut the console down, it will not then switch on again. I can only then get the console to start again by attaching a dead battery and this process of charging seems to be the only way to actually boot. I was gonna try maybe reflowing some chips, but just wondered if you guys had any ideas first? I can’t seem to find a lot of information on the topic to be honest