Dismantling the Nano took only minutes, and I've never done it before now. However, what I was greeted with inside was rather shocking.
It would appear as though my battery has swollen to around three times it's original size and I've narrowly escaped a melting or exploding iPod. The swelling had not only wedged the select button permanently out rendering it, and the iPod useless, but also the front of the casing is actually cracked, a fact I had not initially noticed as it's not easily visible on the white backing.
I'm going to attempt to bring this to Apple's attention, as I believe this has been caused by a bum gravyty in-car charger, however I think Apple should be told just in-case there's a small chance there's a dodgy batch of two year old Nano's out there about to start popping.
We shall see what happens though.
Update: Via some very unofficial channels, I've managed to get this:
humping typical! Do note though, that this response is not the opinion of Apple, nor in any way official. It's a shame I don't live within reasonable distance of an Apple store, else I'd close the bugger up and see what the guys/gals at the genius bar had to say. Oh well.Now its been opened, we won't be interested I'm afraid, anything could have happened to it and we will not be able to determine the cause of the failure.
Update #2: Having probed my lighter socket with a volt measuring device it seems that the lighter is indeed supplying a level of voltage deemed correct for most devices, though it certainly didn't seem to be a steady flow - varying wildly from 9v to 12v - it never heightened to unacceptable levels. I tested late at night so it was dark out, I shall attempt to try out the charger itself, and again test the voltage with the engine running (Only performed a quick test today as I was only in the car to change a fuse). Either way, Santa was kind to me this year, so I am once again not without iPod, however, I'm still interested in why this one bit the dust.
A bad battery charger won't do that type of damage, unless it is outputting the wrong voltage.
There is a circuit in the nano, and all other batteries (take em apart, if you want and check) for mobile devices. Lithium Ion batteries have to be charged a very specific way, and there is circuitry attached to the batteries to make sure this happens. The lights you are able to use at the bottom of a battery from Apple to check it's status is done by a smaller micro controller that sits on this PCB that checks the voltages, temperatures, and other info about the battery.