Iphone 3GS Restoring Problem (Probably Jailbroken)?

So here's my story:

I bought this Iphone 3GS 32gb from this guy for €50,-
It's in Recovery Mode.

First, I tried to restore it normally.
Then, I got error 3194, no problem, I just edited the hosts file.
But then, I got error 1600.

I searched several forums and the answer was iReb.
With iReb I put it in PWND DFU mode and tried to restore it.
But still, error 1600 kept popping up.

I tried it on several laptops and pc's, but it just won't work.
I even tried several different IPSW's, and even made custom ones with Redsn0w.

On 2 laptops and 1 pc the restoring process worked fine,
until it got to 70% and it displayed error message (-1) or (1).
On the internet they say that I must try it on another laptop or pc.

Do you know anything I could try?
Or is it just a waste of time?

I feel like I tried everything. If I didn't give you enough information, ask me what you need please.

Very much thanks in advance!

Wouter S.
(Netherlands)

See if you can get your money back.