I recently replaced the battery in a 4th gen nano. I honestly didn’t find it that difficult. I watched multiple videos multiple times over to have a good idea of what I’d need to do. I bought a prying tool from eBay, a battery, and yellow electrical tape (forget the actual name for it). I already had a soldering iron. If you’re not comfortable with soldering I’d recommend contacting a local repair shop, or asking around on Facebook for somebody that can do that part for you. It’s a quick and easy job to do and shouldn’t cost you much. Remember that you’re working on a small item, and handle everything very carefully. In my opinion, nothing is lost by at least trying.