If you made the same mistake as I did, Upgrading your first gen iPhone to OS 2.0 before using the PwnageTool, you can try this Firmware.

I spent roughly 20 hours unbricking my iPhone and this firmware finally did the trick, so now I have an fully functional unlocked/jailbreaked first gen iPhone running OS 2.0

All you have to do is connect your iPhone to iTunes and enter DFU mode 
(Press and hold home and power button for 10 sec. Release power while still holding home. Hold home for 10 sec and release)

If successful iTunes will tell you that it found an iPhone in restore mode and your iPhone will display either the apple logo or blank screen.

(if your iPhone displays the iTunes connect logo, then try again, you're not in DFU mode)

Problems you might encounter:
I had a lot of trouble getting iTunes to recognize my iPhone as an iPhone.
It kept saying "waiting for iPod" and then failing because it could not identify the "iPod".

I overcame this problem by restarting/reconnecting the iPhone/computer many many times and also inserted a sim card which wasn't accepted by the iPhone (which may have forced iTunes to recognize it as an iPhone)

If you successfully enter DFU mode and iTunes recognizes an iPhone in restore, simply alt click (on mac) or shift click (in windows) the restore button and select the cracked firmware.

Now I recommend that you leave the house for 2 hours so you don't get tempted to restart your iPhone because one or more of the restore steps takes a very long time. (Read: DO NOT UNDER ANY CIRCUMSTANCES RESTART Your iPhone during the restore process or you might brick it!!)

When you get back, if all went well, you have an unlocked jailbreaked iPhone running OS 2.0 :)