fastboot update from 2.4.3 to 4.1.2 worked... mostly

[LoTekGuru]

I just flashed my Nexus S (on AT&T) from Gingerbread 2.4.3 to Jellybean 4.1.2 tonight and everything worked except the phone won't connect to AT&T's network. Sound works, WiFi works, I can play 3D games... just no wireless network connection. I tried re-flashing the radio again, and still no network. Anyone else have this problem? Do I need to re-flash everything again? I used the image pack from Google. I did notice some warnings/errors when I flashed the image-soju-jzo54k.zip file... I don't remember what they were, just that it couldn't find I believe it was 2 files. The image seemed to work though, as when it was done flashing, the phone rebooted and got the Jellybean "X" loading image and it booted without incident (other than the mobile network problem, that is...)

EDIT: wow... 240 views and nobody else is having this problem? that's disturbing :/ I re-flashed all (bootloader, radio, system image) and still the same problem

 

[LoTekGuru]

!!SOLVED!!​

After a couple of hours scouring the web I landed back at XDA (for about the 10th time) and finally this time with a solution! Apparently, the JZO54K radio firmware from Google isn't compatible with the i9020a. I downloaded the most recent radio firmware from this thread (I used the UCKJ1 files), rebooted and BOOM got instant 3G connection. I'll be trying the HSDPA tweak after getting my phone set back up (AGAIN) with all my music and personal settings...