iPhone 3GS won't restore (error 1600 or "not eligible for this build") no apple logo, recognised in DFU mode.

My iPhone 3GS decided to turn itself off (on 30% battery) yesterday and hasn't turned on since. After some testing (hard resets, DFU mode), tiny umbrella recognises it in DFU mode, as does Redsn0w. neither devices can successfully kick the phone out of the restore loop.

The screen stays blank throughout, no apple logo, connect to itunes logo etc. however every now and then the charging sign will appear (empty battery with a little bit filled (red)). even if i unplug it from my iMac the charging symbol stays there.

once I get the phone in DFU mode iTunes recognises that there is a phone connected that needs to be restored, it doesn't matter if I click restore or option + restore the process will fail on Error 1600 or "this device is not eligible for this build".

My iPhone is not unlocked or jailbroken. Before the incident with the coffee I managed to synchronize and update its firmware as indicated by iTunes. The latest update for my iPhone was iOS 5 firmware. My intent is not to unlock or jailbrake the device, just to make it work again.

Here are some things I've tried since:

1. Exiting recovery mode via Tinyumbrella

2. Entering DFU mode via Redsn0w

3. Shift + Restore and using firmwares from 5.0 to 5.0.1 to upgrade my iPhone.

4. Remove hosts to my Host file (in relation to the "device not eligible for this build" issue)

5. Try redsn0w and use IPSW to see if it is recognized by iTunes (iTunes recognizes the iPhone but then at the very last minute shows error 1600.

6. Save SHSH files and use Tinyumbrella to uploaded them to my iPhone.

I would really appreciate if someone can help me on this. I might be doing something wrong or maybe not even considering the right steps to solve this issue. I don't know if there are missing drivers that are preventing the device from communicating with iTunes properly. Of some tool that can be used to correct this problem. It may or may not be fixable but I think it is worth the try.

Thanks very much.