Buenas!
A ver hace un monton de meses intente actualizar mi ipad con poco exito, nunca lo logre, y hoy lo que voy a es a intentarlo con todo, y si no lo consigo lo vendo para piezas, y se acabo, no me vuelvo loco mas! Bien, voy a postear paso por paso todo lo que hago y a poner fotos de todo el proceso... a ver si asi entre todos me echais una mano... mil gracias de antebrazo!
1º Paso, descargo este firmware y es el que intento meter...este (iPad1,1_4.3.3_8J3_Restore)
2º Paso, intento meter el firmware con itunes (la ultima version) pulsando shift+restaurar, entonces se me queda la pantalla del ipad asi...

Despues de un rato esperando (3 o 4 minutos) itunes me da el siguiente error...

Este es el error maximizado que me dio itunes;
2011-06-04 00:01:46.270 [2284:a94]: restore library built Feb 7 2011 at 06:28:58
2011-06-04 00:01:46.270 [2284:a94]: iTunes: iTunes 10.2.2.14
2011-06-04 00:01:46.270 [2284:a94]: iTunes: Software payload version: 8J3 (option key)
2011-06-04 00:02:07.335 [2284:1058]: iTunes: Specifying UOI boot image
2011-06-04 00:02:07.344 [2284:1058]: *** UUID E4B001D6-6CE6-A647-BAA4-FC878F0EBEBD ***
2011-06-04 00:02:07.344 [2284:1058]: requested restore behavior: Erase
2011-06-04 00:02:07.364 [2284:1058]: amai: AMAuthInstallDebugWriteObject: debug object written: C:\Users\FAM~1.POR\AppData\Local\Temp\PerBCCC.tmp\amai\debug\tss-request.plist
2011-06-04 00:02:08.839 [2284:1058]: amai: tss_submit_job: HttpQueryInfo returned 200
2011-06-04 00:02:09.799 [2284:1058]: amai: AMAuthInstallRequestSendSync: received tss response (server version: 2.0.0)
2011-06-04 00:02:09.800 [2284:1058]: amai: AMAuthInstallDebugWriteObject: debug object written: C:\Users\FAM~1.POR\AppData\Local\Temp\PerBCCC.tmp\amai\debug\tss-response.plist
2011-06-04 00:02:10.272 [2284:15bc]: iBoot build-version = iBoot-817.28
2011-06-04 00:02:10.274 [2284:15bc]: iBoot build-style = RELEASE
2011-06-04 00:02:10.275 [2284:15bc]: radio-error = 16
2011-06-04 00:02:10.275 [2284:15bc]: radio-error-string = 'Not present'
2011-06-04 00:02:10.286 [2284:15bc]: unable to open device_map.txt: No such file or directory
2011-06-04 00:02:10.286 [2284:15bc]: <Recovery Mode Device 00B215E8>: production fused device
2011-06-04 00:02:10.288 [2284:15bc]: interface has 1 endpoints, file pipe = 1
2011-06-04 00:02:10.288 [2284:15bc]: <Recovery Mode Device 00B215E8>: operation 4 progress -1
2011-06-04 00:02:10.377 [2284:15bc]: bootstrapping restore with iBEC
2011-06-04 00:02:10.389 [2284:15bc]: <Recovery Mode Device 00B215E8>: operation 31 progress -1
2011-06-04 00:02:11.389 [2284:15bc]: <Recovery Mode Device 00B215E8>: Recovery mode succeeded
2011-06-04 00:02:11.559 [2284:10c4]: WinAMRestore::OnInterfaceRemoval: \\?\USB#VID_05AC&PID_1281#{ED82A167-D61A-4AF6-9AB6-11E52236C576}\IB0000#20f8958a
2011-06-04 00:02:11.561 [2284:10c4]: WinAMRestore::ProcessDevNodesChanges: device: 0x0822c9b0, notify: 2, connected: 1
2011-06-04 00:02:11.561 [2284:10c4]: AppleDevice::NotifyDisconnect: IBOOT, IBOOT \\?\USB#VID_05AC&PID_1281#{ED82A167-D61A-4AF6-9AB6-11E52236C576}\IB0000#20f8958a, inst: 0x822c9b0
2011-06-04 00:02:11.561 [2284:10c4]: IBOOT, DFU \\?\USB#VID_05AC&PID_1281#{B8085869-FEB9-404B-8CB1-1E5C14FA8C54}\0000#20f8958a, inst: 0x822c9b0
2011-06-04 00:02:11.562 [2284:10c4]: _AMRecoveryModeDeviceFinalize: 00B215E8
2011-06-04 00:02:11.568 [2284:10c4]: WinAMRestore::OnInterfaceRemoval: \\?\USB#VID_05AC&PID_1281#{B8085869-FEB9-404B-8CB1-1E5C14FA8C54}\0000#20f8958a
2011-06-04 00:02:11.569 [2284:10c4]: WinAMRestore::ProcessDevNodesChanges: device: 0x0822c9b0, notify: 2, connected: 0
2011-06-04 00:07:11.642 [2284:a94]: iTunes: Restore error 1604
Bien, sigo...
Despues de probar con iREB-r4 en el programa me sale el siguiente mensaje despues de poner el ipad en modo DFU.

Y al volver a intentar cargar el firmware con itunes, me salio otro error diferente, error 28.