How I repaired my iPod Nano 5th Gen
My iPod battery with a full charge only last 90min of playing music or a few minutes (around five minutes or less) of video playing. Now it works awesome! I can listen music for hours in a row.
Some steps were quite easy, some were very hard and other were tricky. Open the top and bottom caps were easy, the tricky part was to take off the glass panel because of the adhesive band all over the perimeter, I highly recommend to take off the glass panel taking care of keeping the adhesive stick to it, otherwise will be hard to slide the internal device of the case. The hard part was the de-soldering and the soldering of the battery. I need help of another pair of hands in some steps as when I was taking off the glass or when I was doing the soldering because the device wasn't stable.
Be careful with the glass panel adhesive, with the process of taking off the adhesive of the battery (the one inside the iPod, no the spare), with the soldering (you might puncture the old or new battery or cause a short). Also, If you're using your bare hands the screen will get dirty, use microfibre towels and isopropylic alcohol for the cleaning.
Take care that you have all the tools listed in the guide, they are very helpful, in particular the screwdriver and the metal spudger.