Ipad in DFU not recognized by itunes nor by pc

Hi,

I have an ipad1st gen a1337, which is stuck on connect to itunes logo. When connect to pc it is not recognized neither by pc itself (nothing in my computer or device manager) nor by itunes. Tried putting it in DFU mode, still nothing.

Tried using tinyumbrella and redsn0w but still not recognized.

Tried it on 2 different pcs and with a bunch of different cables, no luck there! PCs and cables work fine btw. Tested million times.

Replaced the dock, which actually charges the ipad and home button works but still same problem.

Is it time for it to go or anyone has a slightest clue what can be the reason?

THanks!