I restored and unsuccessfully attempted to activate a factory-unlocked 32gb 3GS that I was previously using with a software unlock. What did I do wrong?

AT&T did confirm the unlock request was accepted and processed. I waited beyond the 7-day window they recommend. I am no longer able to access anything on the Springboard, therefore cannot look up IMEI/Serial# or other pertinent information. I was also foolish enough to not write any of that down. The box that I received with the 16GB is not the original, because the SN and IMEI do not match. It is unlikely the box for the 32GB is the original, but, again, I cannot confirm. I have another 16GB 3GS I was operating in a similar fashion on Tmobile. If I bricked the 32GB, I would like to avoid making the same mistake on the 16GB. Both devices were purchased in the secondary market with the appropriate software (Cydia, etc.) already installed. I have seen several suggestions regarding downgrading the baseband before upgrading, but I thought restoring/upgrading the iOS would automatically change the baseband to the correct one. I am unsure of the baseband on the 32, but I know the 16 is operating on the 6.15.00 iPad baseband. What, if any, steps did I miss during the restore and activation? What new steps should I take with the 32 to activate with the factory unlock? Which carrier's SIM card is needed during the restore and activation? I am only attempting to clean these phones for resale, so I was not originally concerned with preserving any of the jailbreaks, tweaks, "test apps," etc. Any thoughts and suggestions will be read and appreciated!