Chosen Solution
It was a water damaged switch, managed to pretty much fix it up, but the battery doesnt charge on itself, it shows the charging icon on dock and handheld, but the battery percentage just keep going down as it doesnt really seems to charge itself.
The charge circuit may well be faulty. You may have to replace that and the battery just to be safe.
I be replacing the batttery first Nintendo Switch Battery Replacement
Having this same issue but my switch isn’t water damaged. The battery has been replaced and have tried 2 different switch chargers. The battery still depleted while on the charger.
