I have seen this happen a few times before and the way I have always managed to resolve it is by running a command in single user mode to modify the drive so that it thinks account creation was never done. So you can create a new admin account. Grant admin to the account you want and then ditch the account you just made.
There is a fairly comprehensive step by step on this here:[br]
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https://logi.wiki/index.php/Single_user_mode