Recovering a former Employee's Mac,

I have a former employee's Mac that I set up quite awhile back. In the recovery process, it says it is linked to an account and shows me the partial a.....@f.......com. I know what that ID is as an old admin account we used to use. I could not recall the password because it had been some time. When hitting forgot password, it did show the partial phone that matches mine, and still would not reset. I opened a case with Apple and had to wait the 2 weeks for them to call me back. They helped reset the apple password with ID that matches the partial info that came up on the current paperweight of a Mac. But now when I log in using the recovered credentials I get This Mac is linked to a different Apple ID. Any ideas on next steps? The partials shown match everything that Apple reset for me, so how can I now still get this message?