I’d look over the following topic as your symptoms are virtually identical
Given the WIFI IC was getting hot it likely indicates the chip was internally shorted or corrosion below was causing a short, so ideally you’d check on surrounding components on these rails and measure the resistance to ground to verify the fault condition before and after replacment of the IC while comparing to a known good
And to add, stock standard IC’s will not work on Switch, so either have to be preprogrammed specifically for Switch or pulled from a Switch donor board, I would also take a very close look at the quality of the balls on the IC as many supposedly “new” chips from China are obviously used and poorly reballed