Need Help Fixing No Sim Problem

Hi,

A few months ago I jail broke my Iphone 3G with the 4.2.1 firmware. Recently, it had been crashing regularly so I decided to do a downgrade. Using the shift-click method, I restored to 3.1.3. I then fixed the 1015 error using iREB. The problem now is the iphone will only show the screen saying "NO SIM card installed: Insert a valid SIM with no PIN lock to activate iPhone." The same SIM I have always used is currently in the phone. Hoping there is some way to fix this.

Thanks alot!

PS: My sleep button is broken aswell so any solutions involving DFU mode must require a way of getting into DFU mode without the sleep button

 

I doubt it is a hardware issue because the iphone experienced no trauma between before the restore (SIM worked fine) and after. Also, the SIM card currently works fine in my old phone.

EDIT: Unless a software change could somehow affect hardware...?

 

It only did it after fixing the 1015 error with iREB and it has not gone away since