Board damage, incorrect reassembly and leaving flux such that it messes with contact of things would be the main things to cause that sort of thing.
The latter two are the more likely as I assume you would have noticed the first. Take it apart, look for any obvious damage (or take a decent photo and share with us), clean the board and reassemble it properly. Or if you can see obvious flux residue on the pins or something and can clean it without disassembling then do that if you want.