iFixit has taken apart the seventh-gen iPod nano to get a look at its innards, and found that this guy — like most Apple products of late — is pretty difficult to repair.
Basically all the important parts have been soldered to the logic board — the battery, the lightning connector, the button cable, and the headphone jack. The battery — which is 3.7 volt, 22 mAh, and 0.8 Wh (twice that of the sixth-gen Nano) — is also adhered to the display. However, the LCD screen and the glass digitiser covering it aren't stuck together, so you can probably replace these parts much easier. This new music player also has Bluetooth, so there's a tiny antenna inside. Additionally, it has flash storage from Toshiba and a touchscreen from Texas Instruments.
Also of note is that the clip is gone and of course Apple made the switch to the lightning connector, so this iPod is obviously much thinner, although it's gained a just under 10g. Just be careful that it doesn't slip out of your hand. [iFixit]