"Account limit reached for this profile" after my little brother tried to sign in?

Hello, My little brother signed me out of my mozilla account while trying to login to his school account using my computer yesterday. Now, even after signing his account out AND removing his account entirely from my firefox, I'm unable to login using my credentials on the "original profile" which is what I've always used. This is the message I get when trying to login: This profile was previously synced to a different account To keep your data organized and secure, each Firefox profile can only be synced to one account. To sign in using (email)@gmail.com, create a new profile. He wasn't even able to fully login with his account, and even after completely removing his account from my firefox (as far as I know) I'm not able to sign into the original profile at *all*, even though that's what I've always used. Does anyone have a solution for this?