Here's how this great franken-experiment is going. At this point. I've ripped off the connection board from the previous old battery. To this board, I've connected the leads from the USB wires. Then I've connected the plug from the old battery board to its place on the phone's motherboard. Polarity is correct, at least from what I've seen online. So when you say reinstall the battery, I don't understand because there's no place to put/connect/attach said battery because the connection(s) from the USB wires and plug from the old battery board are taking its place. Dig? Is there anther way to try this? So effectively, there is no battery, just straight juice from USB power. I've tried from both computer and charger. Got nothin'. No joy. So sad. Oh, wait, there was that "unknown USB device needs more power than the port can supply," warning coming from the computer is that means anything. I'm searching for other things to try. Keep in mind, I have no idea what I'm really doing which kinda makes this fun if not very futile and frustrating. Ha!
Well, it sounds as though you have made a great deal of progress, actually.
So, we know that there is not enough power via USB to power the device.
This is common.
You will need a real charger hooked up.
As far as transfering files, use NitroShare to do it wirelessly.
It may be that you still need to integrate the battery, maintaining polarity.
It does not need to be inside the device, but most likely will need to be connected even if it is dead.
The device is designed to run from a battery, and there is circuitry in the device and in the battery to try to ensure that this is the only way to run a device.
Yes, it sucks when faced with this, but look at what you have learned so far, and the skills and experience from some hands on DIY work.
Even if the end result is a failure, it really is not.
The lost data as a price paid for the knowlege?
Most likely quite a deal, although it may not seem to be right now.
Believe me, I have lost data.
It is crushing.
But in the end, life tomorrow is whatever it would have been anyway- data lost or not.