error 23 iPhone 4

hi, my cousin dropped his phone so i replaced the back for him. an easy job. when i plug a power cable into it it does nothing. the only way i can get it to power up is to disconnect the battery while the phone is still plugged in to the lead, the apple logo comes up and after a while the phone powers up in restore mode. when i try to restore it via itunes it was coming up with error code 1611, after playing with the phone it is now coming up with error code 23. my itunes is the latest version, my version of windows 7 64bit is upto date as is my security software. what else can i try.

this problem must be connected to the fact that the phone was dropped, in an attempt to find a solution i have fitted a new dock connector which didn't help. and another battery (not new) but neither have helped.

any help would be great.

many thanks, lee