Hi J Johnson.
Welcome to the forum. Sorry your first post here is for a problem, please could you tell us which model of camera you have the problem on. There are people here with in depth knowledge of most models, but I fear you may have answered your own question, a trip to canon may well be in order. There was recently a post detailing how to re install a firmware version, though I don't think you will get far if you can't get into the menu!
7DII+Grip, 7D+Grip, 40D+Grip, 5D+Grip, EF 24-105 f4L EF-S 17-85, EF-S 10-22, EF 70-200 f2.8 L IS II, EF 2x III, Σ150-500, Σ17-70 f2.8-4 C, EF 50mm f1.8, 550EX, Triopo TR-985, Godox FC-16, Filters Remotes Macro tubes Tripod heads etc!
5D, 20D, 24-105, BG-E4, BG-E2N, 17-85, Nifty 50 pre owned. 😀