If any user of Classroom Monitor fails incorrectly to login 5 times in succession their account will be locked.

To unlock a users account you need to have either administrative or SLT permissions on your account.

Go to Teacher Management within Settings under the School Configuration heading and locate the teacher you wish to unlock, click the row of that teacher on the table and you'll be redirected to the edit teacher page where you will see the button below:

Click this button and then press save and this will now allow the user login again.