Don't worry, it's not as scary as it sounds.
As part of most Financial Institutions' (FI) security measures, they may lock a bank account for different reasons to protect you. One of the more common reasons is that there may have been too many failed login attempts to your bank account.
Since this is on your FI's side, we would need you to contact your FI and have the account unlocked so that you can continue to earn cash back.