This also happened to me that my GC key was revoked. I just made a new account using the same email address. Then you can link/retrieve your applications using the UCI numbers. Although, I decided to use the new IRCC portal to renew our visit visa.
Just wondering, my sister applied for visitor visa recently and got her Biometrics done on May 4th. She applied through travel company. They are not giving login id and password as they apply for all of their customers using same login. Now my question is, can I create a login and link my sister application so I can check status myself??