I have jailbroken my ipad 4.2.1 just like the video, It was working fine until I needed to shut down and reboot (ipad). When I came to reboot I could not boot in thethered state via redsnow. Which I have done before. after many attempts I thought I would try and restore via itunes. Which does not work either, have i KILLED my ipad? What I have found is when I plug it into itunes it does not recognize it, nothing shows up under devices but it beeps when I plug it in, I get the itunes logo and usb logo on the ipad but nothing happens on the PC. I have tired several usb leads and different ports. When I try and boot in tethered mode it beeps 3times (weird usb noise) then tells me i have not followed the instructions correctly. IS MY IPAD DEAD?