iPhone stuck in a boot-loop + Error code: 21 upon iTunes restore?

Hello, recently bought a few iPhones as I am looking into making an application I have developed cross-platform.

This particular iPhone did come working (booted) with a cracked screen, I had purchased another screen and had fixed the iPhone but unfortunately had a pass code, I didn't see this as a problem so I installed iTunes and attempted to completely reset and restore the iPhone; I did remember the iPhone only reaching around 40% on the 'loading' bar on the phone before iTunes presented me with an error code.

I cannot remember what this error code was, but it escalated until I finally ended up getting the error code: 21, and it's pretty much stuck with 21 upon every restore attempt.

I had opened up the phone and noticed the battery connector had now became loose and has now detached from the logic board, upon doing my own research on Error code: 21 I had presumed this battery connector was the issue. (Or is it something else)

So my question is, is there a possible way to restore this iPhone 4 WITHOUT iTunes (as my plans was to purchase a charge case to keep it alive when making it portable if needed). Or will I simply have to re-solder the Connector on myself? At this very moment the phone powers on when the charger is connected HOWEVER, presents the Apple logo for around 10 seconds and re-boots (bootloop) which has lead me to think the OS has corrupted upon trying to restore the very first time.

Thank you for any help given, it's greatly appreciated!

-Jerrelle

tl;dr - Battery connector is broke, phone is in a bootloop, will I be able to restore this iPhone without iTunes and cure it from the bootloop without having to physically repair the connector?

Extra Information

*iPhone 4 - 16GB

*I have no history whether it has been jail broken or not. (Most likely has).

If anymore information is needed I will supply, thank you. :)