1300D error 20 and shutter is rapidly opening and closing when off

Heya,

Got a confusing problem today.

Took the camera out today in some light rainfall (This camera has gotten wet before and has never been an issue) and got hit with an error 20 message after about 30 minutes. What's confusing is that the shutter rapidly opens and closes, even when the camera is 'off'. This obviously stops when I remove the battery.

Took the lens off and had a look, nothing seems broken.

I put the camera in the hot press beside some silica gel in case it is water damage but I was wondering if it is something else.

Any answers would be appreciated.