How do I identify my iPhone 5 short?

So I have an iPhone 5 that was brought to me by a customer as a water damage repair. It was actually still turning on when he brought it in. I am not the store owner, but I am a technician who would like to be able to take my repairs to the next level. We have only recently started desoldering the shields on the iphone 5, so obviously we weren't doing everything we could on the water damage side.

However, after we desoldered the shields and ran it through our ultrasonic machine (doesn't have sweep frequency) it would no longer power on at all.

I noticed that there was a something on the board that was getting extremely hot. However, I know very little about circuits. I don't know how to identify capacitors, resistors, or any of the other common parts found on a board. I don't know the properties of said parts, and I don't know what anything does.

However, doing the actual physical act of soldering isn't too difficult for me. My problem is finding what needs to be fixed and what is possible to be fixed.

Having said all that, what I found to be very hot to the touch, to the point where it would burn me was labelled L15 on the board view. It is right next to the U7 chip.

Here is a picture:

http://imgur.com/a/xkzUX

Its the thing with a little white dot over the thing with the "L" on it.

I actually removed it from a donor board and tried to replace it on the new board. However, the phone still doesn't turn on and the chip is still getting extremely hot.

Is there any advice as to what can be done?