I had this issue with a sprint Iphone 5. Disconnect the battery and plug the phone into the computer. IT will power on. Use tiny umbrella to force it into recovery and install ios.. You will get error 2001.. Once that happens.. Unplug the phone and connect the battery. Force the phone into recovery with tiny umbrella and install ios again. If you are still in recovery use tiny umbrella to force the phone out of recovery.
This issue is a hard one to fix. Error 2001 has to do with a bad battery. Previously I disconnected the battery and booted the phone up with it plugged into the computer and tried restoring it. That is when I got the error. What I did was replace the battery with a new one and used tiny umbrella to force it into recovery. Then installed iOS. It worked perfectly afterwards.