Unable to activate iPad 1 IOS 5
I have an Ipad 1 IOS 5.1.1 64GB 3G and I cannot activate through Itunes neither Wi-Fi. I have the latest version of Itunes installed. The Ipad is At&t carrier (unlocked). I tried everything in order to activate but I could not make it. i tried with the sim, without it, the next next next trick, DFU mode, Recovery mode, Recovery Fix with Redsn0w, Tinyumbrella. It had been working great before I restored a few days ago. It is NOT a hardware problem. It reboots every 3 minutes. What Should I do? Of course it is out of warranty. That's the first Ipad. Thanks in advance.
iPad, iOS 5.1.1