45 minutes - 2 heures
The Nano had stopped holding a charge.
Fairly well given the very high difficulty of the repair. The end result was success.
Desoldering the old battery was definitely the hardest part. Desoldering braid is a must, however it was impossible to remove every last bit of solder necessary to free the wires. I had success placing the shaft of a small screwdriver through the loops of battery wire on the backside of the board and using it to apply tension to the wire while heating the front side with the iron. With tension on the wire, it would pop free from the board once the solder pad was heated. I also needed to use a pin to ream out the holes in the board just a bit to get the new battery wires through. A hands-free magnifier was also very helpful in making the repair.