In September 2010, Apple unveiled the 6th generation iPod Nano (Model: A1366).
The new Nano is a significant departure from previous versions--resembling the new iPod Shuffle more than older Nanos.
As with the iPod Shuffle, the Nano isn't designed to be easily disassembled. But if you're working on a device that's already broken and out of warranty, you might not have anything to lose.
To disassemble the iPod Nano, you'll need a Phillips #00 or #000 screwdriver, a thin metal blade or plastic spudger, and a hair dryer or heat gun.