mdench
You need an admin login to update this. Ask around for an admin account or have someone create it for you. If you have one but can't login as it's locked to OAuth2 then 1.) You are always supposed to have an admin with local creds specifically for cases like this 2.) you will need to go to the db, _staff table, find the staff record, and set their backend to NULL. Once you do this and can login you can navigate to Admin Panel > Manage > Plugins, click on the OAuth2 plugin, click the desired instance, updated the secret, make sure nothing was auto-filled by the browser, and save changes.
Cheers.
