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Probably not the best time to clear your head but I'm sure (ISC)2 will help you out soon, if they didn't contact you already.
Unfortunately same thing happened to me today. Also unfortunately ISC2 won't do anything about it. I literally let the proctor sign me in on the computer. I immediately start to write down my mnemonics and formulas for the test. I'm sure it wasn't 5 minutes but ok, and without a warning or anything it kicked me out. Pearson did open a case for me also but ISC2 was pretty firm that they wouldn't do anything about it and I'd have to purchase and schedule another test for the full $750. I've never seen this on Pearson or ISC2 website. If it was mandatory to sign it would've been nice to have a proctor or BOLD notice that it is required within a time limit. Here I am trying to save time on this 3 HOUR test and I end up losing $750 for using smart testing techniques. Hope you have more luck than I did.