I think I bricked my girlfriend's phone

Yeah im pretty sure by the way you described things official 2.2 is out yes.. But you shouldnt have tried to flash unofficial firmware 2.3 gb without properly loading the bootloaders.. This I am quite certain was a mistake which you happened to stumble apon via google or some other search engine and didnt realise what you were doing. I would say a JTAG is the only solution if successful, But your best bet is to take it to at&t or Best Buy if you bought it there and their insurance hopefully and say you dropped it on the ground and that the screen doesnt work anymore. then let them replace it.. otherwise hopefully you have some kind of insurance on your phone. And dont even attempt JTAG unless you want to break your phone apart and possibly risk not even being able to return it at all especially if you cant update to 2.2 official or not.