Help Sl2 Went Screwy on Me

Hi Everyone, I am hoping someone here can help me sort out what might be wrong with my camera (Sl2) or lens (70-300 USM II nano) or both.

Basically, I use this set up for bird photos from my kayak. Several months ago I flipped the kayak and my unprotected camera bag ended up floating nearby.  I rescued the bag and the camera seemed completely dry and seemed to work fine. There was no water anywhere inside it and the bag kept it pretty dry. Kudos to Canon for that one, although this could still be the source of my problems.  The way the bag landed, water got into the lens and immediately wrecked the electronics in it. It was toast, no question, and I replaced it with a new lens from Canon refurbished.

Everything worked fine when I first took the camera out, and I got some wonderful shots, then it stopped working right. It could neither auto or manual focus, the Q screen wouldn't come on, playback wouldn't take place.  I changed the battery, didn't help much. gingerly unscrewed the lens and put it back on, that did help but sometimes continued to have issues.  The only thing I noticed (since when I was having problems that lcd screen went black) was an !  (exclamation point) in the viewfinder. It might have been generating error codes, but I couldn't see the screen.  Then it started working again and is working seemingly ok now.

Any suggestions about what might be going on.  I can easily take it into Canon, but am guessing they won't touch it because of the way I am using it, exposing it to salt water, etc., so any suggestions will be useful.