Charge an iphone4S without charger?

I bought the iPhone 5S and of course my charger port on my 4S died as it was about to that week. So now my phone is dead as I walk into Best Buy. They said that if they could JUST turn the phone on to see that all the buttons work and stuff then I could get a $200.00 credit. Well of course the charger port is dead so they told me that I have 15 days to figure out a way to get power so they can see that it's a good phone (Charger port withstanding of course)… How do I charge this without a charger… I heard that charging pads don't work cuz they must plug in for a backup charge.

Ask around, look for people in the street with the same phone. And see if you can borrow a charger.

Actually chargers are the most commonly left behind item in hotel rooms
You could try ringing or popping into some hotels to ask if one was left behind. Maybe pretend it was you that left it. Although that may not work. Best be honest even if they let you just use it for a short time.

Go to Apple. They have great Tech guys. Ask them. Or raise Ben Franklin from the dead and have him put your dead phone on his kite. LOL