Its possible the seal broke down and the sweat found its way into the back side of the crystal which is where the OLED and touch sensor sit. Ifixit only has the 44mm still in stock [product|IF449-002]. Its a bit of a process to take off and you still need to get the seal gasket as well. Here's a reference on the process as we don't have an SE 2 guide but its mostly the same [product|IF449-002].
You may want to just get a new watch as its likely the battery is on it last legs as just the parts alone is close to the same costs of a new watch.