Sorry about your camera. Hats of to you if you are able to change these things out. The display is one thing, but the PCB sounds like it would be a little more challenging.
When a camera gets that wet, internal corrision it usually what can kill it. Sometimes they dry out, somethimes they don't.
Can we assume you have performed a full reset? If so, you are at a crossroads.
It's time to send the device to Canon, or walk away. Depends on how much money or time you want to throw at it.
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The moisture that got into the controls likely has it appearing to the control board that more than one control input is being constantly activated. Although fresh water isn't great for electronic stuff it isn't that harmful by itself BUT the oils and salt from your skin along with other environmental debris which were carried into the controls along with the moisture leave a residue that stays conductive even after it dries.
In cases where it is possible to isolate the switches and push buttons from the rest of the camera, flushing with WD-40 works well. WD-40 was originally developed to displace water and all it leaves behind is a light oil (which also evaporates over a few days) that is non-conductive. I have used it often in restoring vintage electronic gear as a flushing/cleaning agent BUT you have to be very careful not to get it where you don't want it ESPECIALLY in a camera. One of the world's leading test and measurements equipment firm released a service note several decades ago after testing various contact cleaners and found that WD-40 provided the best results with the very expensive precision potentiometers used in their instruments.
With some vintage radio gear that I restore, I start with a thorough flush with distilled water and then use WD-40 as part of the cleaning/drying process. But I wouldn't use that level of cleaning with a precision camera. Good luck getting your camera going again.
I actually ended up buying an eosr to replace the 80D but I figured since it still takes pictures I could mess around with it and try to fix it as a hobby lol. But I was thinking it was the main board being the issue.
Under those circumstances I'd suggest that you open all the camera's orifices, place it in the driest environment you can find, and let it sit for four to six months. If it then works, send it to Canon for a professional cleaning. If not, see if anyone will buy it for parts.
"... place it in the driest environment you can find, and let it sit for four to six months."
I'm all in on this idea. Except you don't probably need 6 months. Put it on a warm, not hot, heating pad for several weeks. If after that it works, you are golden. But if it doesn't, it is toast so pop it up, its done.
Water and cameras do not fair well together. I would not even think it a good parts camera if the drying doesn't work.
What if I change the PCB board? I mean it still takes good pictures lol
I think you should regard that camera as 100% unreliable. If you do not know how to troubleshoot the camera, it is best not to start experimenting by changing out parts. You would be spending money that would be best spent on a more reliable camera, a new oone.
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