Help Wifi not working after unlock

[poppynogood]

I have an Express that I use in the States with AT&T gophone. I paid a guy at a shifty kiosk to unlock it for me so that I can use it temporarily in Canada with Virgin prepaid. It works with the new carrier, but now I can't toggle wifi on (it jumps back over to 'off'). The guy returned the phone to me, running 4.0.4. It now says "IP address: Unavailable," which I have to assume is the main issue with wifi. Mobile data works fine, but isn't ideal obviously.

I've done a factory reset, talked to Samsung and ATT technical support for hours. I assume updating to 4.1.2 will help, but I tried this (using a version of Odin for OSX) and it didn't work. (I think may not have had the correct .tar?)

Can someone tell me my options? Can I find 4.1.2 without wifi? Should I root? Can I root using my mac?

Any advice is very much appreciated!

 

[Rukbat]

Rooting has as much to do with wifi as rice has to do with moon particles.

Evidently whatever the "guy" did to "unlock" the phone did a few other things - like mess up the wifi radio. Either the phone's not trying to connect properly or the DHCP client (part of the phone's wifi firmware) isn't working, since that's what obtains the IP address.

 

[poppynogood]

ATT suggested I return it (it's under warranty, they don't know about the unlock obviously). Will it be obvious that I've tampered with it if I give them my device?

Can the issues you mentioned be fixed, in your opinion?