Iphone 3g, 4.21, 6.15 gps fix?

[Xellos2099]

I am helping my friend to unlock a iphone 3g. I realize that it is on 4.21 firmware, modem 5.15 and bootloader is NOT downgradeable. The only choice to unlock this phone that I know of would be to go to 6.15 ipad baseband. I KNOW this is the kingdom come of iphone, no chance of going back. I heard story that if i updated to 6.15, there is chance that the gps would stop working and another rumor claim if I downgrade the phone firmware to 3.12 and with baseband of 6.15 and the gps would still work. Can ANYONE confirm it?

 

[PsstGreek]

Even if you downgrade the OS, the GPS will still get fried.

 

[dhlizard]

Yep, installing the iPad baseband is a one way trip, you cannot remove it.
Nor can you fix the fact that installing it breaks your GPS forever

 

[Xellos2099]

ok... problem, i used the 6.15 and i confirm the phone work with tmobile sim card. However, I got a email from my friend he might have kill the phone.
He uploaded his old files from the dead phone into the new one and it was running slow so he tried to restore to factory settings and now there is only an apple on the black screen. I tried connecting to the computer and the computer does not detect the phone.

I am not sure what went wrong.... should i force dfu mode to reboot?

 

[Applejuiced]

If he tried restoring it to stock firmware then the bb is unstable.
You need to restore to custom JB ipsw and then reflash the ipad bb with redsnow.
And btw, the iphone 3G is slow. Very slow not matter what you do tell your friend.

 

[Xellos2099]

I doubt firmware was reinstall, was there a factory reset button on iphone?