i had a 3gs (old bootrom) running 4.2.1 and unlockable ipad baseband 06.15.00. i was able to run the thing on tmobile and it worked perfectly except for one thing: wifi. no matter the proximity to wireless router, network settings reset on iphone, or router reset, i couldnt pick up a signal. i had to do a wifi-less install of ultrasn0w in order to get my SIM to work. finally frustrated with my lack of apps, i reset and used tinyumbrella to kick my phone out of DFU to install 4.1 firmware and keeping my 06.15.00 baseband. now im back to the locked screen and it seems that no matter what i try, i cannot jailbreak the thing again. ive tried using redsn0w to rejailbreak it on 4.2.1, but im stuck at the "waiting for reboot" part and cant kick the iphone into the part where all the text starts scrolling up on the screen and it jailbreaks my phone. ive tried clicking the 'install cydia' option and the 'just boot tethered' option in redsn0w. i know that there was a redsn0w warning about having 06.15.00, but does this mean im totally screwed? is there no way to jailbreak this thing again? can anyone offer any insight? thanks!