I changed the rear housing on an iPad 2, which requires you to remove the battery and upon completion I powered it on and as soon as it made it to the lock screen I slid to unlock and 2-5 seconds after seeing the home screen it would go blank and the apple screen would come up and repeat (loop) and if I did not unlock it, the same thing would happen within 5 seconds. The battery was not in the red. My fix was to go back in and disconnect the battery and clean the contacts with alcohol, air dry and reassemble. I don't seal the screen in until all systems are go. This worked! No loop! Good luck...
Try a different cable or unplug and re-connect your cable until your iPad shows on your iTunes screen again and let it re-download the software my iPad lost the iTunes connect image on the iPad screen to download finished but it gave me error 39 second time downloading I will give you my results because I am doing the process as I speak. Also the iPad that I am working on is not one that I have had iTunes signed in on my computer so it did not ask me to trust it because your iPad will not do that unless is operating in the normal iOS mode where you see your apps on the screen. I will report back when I'm finished...
In my case I did actually fix my own problem, I disconnected the battery by removing the logic board cleaning the connectors with alcohol allowed to air dry and reassemble. It worked perfectly no more problems. Thanks guys for your input have a great day !
I am answering my own question just in case someone else needs to know FYI . No they are not as the logic boards are different and they mount with screws in different locations and are not interchangeable. The mounting area for volume, mute and power switch ribbon cable is different as well.
There are quality digitizers with quality adhesive from suppliers like iFixit or Mobile Defenders... Hint sellers online like Amazon is not a good choice, unless you have proven that the seller has quality parts. The black adhesive is best and the clear is "cheap jelly" to say the least! I have perfect seals with the black and constantly coming unsealed with the clear mess... Hope this helps.
I was working on one that did this without dropping it. The display did not show except for a flash when you press the wake/sleep button. I did the bump method on it after some research. It recovered to full bright clear display, then I opened it up and replaced the LCD cable and sealed it with Kapton tape. The cable was probably not bad but it was not expensive so I replaced it anyway.
Even if you forgot your security questions you can call Apple and verify you identity and they will help you reset the password. That is if you are the valid owner of the device.
If new battery was criticality low in charge, it will boot loop. Put iPad in freezer for 30m and immediately plug to charger when you remove it. Reason: too low % on battery after repairs won't allow to boot so loop occurs and you can't charge a device in a boot loop. Freezer forces an emergency shutdown and will stay off till temperature is normal by then you should have enough charge to boot. Hopefully this helps!
Also once it is unattached from the front panel, if the antennas adhesive touches the glass again it can re-adhere to front panel and may rip apart after all. Keep a close eye on it or leave a pick or card in there to prevent it from re-sticking.
If new battery was criticality low in charge, it will boot loop. Put iPad in freezer for 30m and immediately plug to charger when you remove it. Reason: too low % on battery after repairs won't allow to boot so loop occurs and you can't charge a device in a boot loop. Freezer forces an emergency shutdown and will stay off till temperature is normal by then you should have enough charge to boot. Hopefully this helps!
If your screen is broken or shattered there are no worries with the digitizer cable, It is all on the new screen.
Also once it is unattached from the front panel, if the antennas adhesive touches the glass again it can re-adhere to front panel and may rip apart after all. Keep a close eye on it or leave a pick or card in there to prevent it from re-sticking.