So, I've seen this being posted round a lot of places but none seem to give me the answer I need, so here goes: I have an iPhone 3G, I updated it to Baseband 6.15.00 in order to JB it on iOS 4.2.1. After this happened, the iPhone became very very slow and GPS didn't work. So I decided to try and revert the iPhone to 3.1.3 software but seem to have done a lot more damage than I had thought could happen... I need some help to at least turn the iPhone back on so it works, any fix will do for now. I have tinyumbrella which informs me my FW version is 3.1.3, and the installed BB version is 06.15.00-5.9_M3S2. Basically, I have tried restoring it to 4.2.1 just through iTunes, I have downloaded a custom FW 4.1 which I am going to try and install through iTunes, but the iPhone has to go into DFU mode first which is appearing to be a problem on my phone also because it is stuck in recovery mode even if I purge it out with tinyumbrella. Any help would be much appreciated.