However, when I started using the phone, iTunes alerted me of an iOS 4.2.1 update. Apple's upgrades I thought should be rock solid, and I proceeded without any hesitation. How wrong was I, for I've been hit with the infamous error 1015.
Questions raced through my mind. Did I just crash the only iOS device I had for testing? Will I be made to pay for this(I haven't even got my first paycheck)? How am I going to complete my project?
Thankfully, a quick google of "iPhone 3G error 1015" revealed quite a number of youtube videos on fixing this. I referred to the video below and it worked for me. Watch at youtube.
After recovering from error 1015, you might need to unlock your phone if you don't have a valid SIM card. Watch at youtube
*NOTE: I used Redsn0w, v0.9.6.rc9, to unlock iPhone 3G on iOS 4.2.1 because, v0.9.6.b4 links was not working anymore.
All required software are listed at video's descriptions at youtube.