What failure?
I see no mention of any failure here. This is disassembly for the sake of education not repairs isn't it?
My 5 runs quite cool most of the time.
I am currently logging my battery to judge it's performance. So far from the user reports I am hearing - if there is any issue it is iOS 6, but not sure if any issue at all.
There is an issue with Telstra in Australia and something pinging the network every second instead of every minute apparently and a fix on the way.