Chosen Solution
Hi @poppypips, When a electronic component gets very hot it is an indication of excessive current flow. Check your work for any short circuits i.e. solder bridging between two connections when it shouldn’t be etc. Use a magnifying glass if you have to. Presumably you removed the battery before doing any further work inside the device? The power button is not a power isolating button so there is always power somewhere on the motherboard when the device is off. Think of the device as being in an extremely low power state when off and not that it is totally disconnected from any power. Check the motherboard over as you may have accidentally moved or disturbed something else during disassembly, repair and reassembly. Here’s the ifixit Nintendo Switch Repair guides that will help. if it is still hot afterwards take it to a reputable, professional electronics repair service and ask for a quote
sounds like either the sd card port is busted or the sd card, sounds like if its charging and working okay then it should be safe to use.
