SEUS Updated to CID 53, Can i unlock with IMEI?

Sad story.
I have a new AT&T W580i (CID52), unlocked successfully with SEtool2.
One day, i updated with sony ericsson update service (SEUS), and my phone became CID53 locked to AT&T.

Now, can I unlock the phone using IMEI unlock code, which can be purchased from ebay?
I think they access the AT&T database and find the unlock code according to the IMEI.

Thanks.

Yes you can use the IMEI unlock to unlock it regardless of your firmware. Once you unlock using the code, your phone will be permanently unlocked. If you've had AT&T for longer than 3 months you can call and ask them to provide an unlock code. Just tell them you're going overseas for a few days and you want to use your phone there. They'll provide you the code free.