Hi Jonny,
I’m thinking that maybe the processing hardware could be damaged. But honestly I would say that it’s time for an “upgrade”, time to get a new camera. Sometimes life just decides to make things not work anymore because we need to move on to better things.
With this in mind make sure you get warranty for the new camera you plan on getting. This way if anything like this happens again, you can just simply replace it for a new body that works.
I know that my answer doesn’t really solve your problem but it’s still a viable option.
Best,
Emmanuel Reyes