Both my wife's iPod Mini and her friend's iPod Nano had terrible battery life, and recently the Mini started showing the "Sad iPod" icon. I thought if I replaced the battery, the Mini might get a proper charge, and I could also check the hard drive's connection.
Overall, the repair was 50/50. The Nano change over went well, other than the control wheel's connection coming apart just as I fed the rest of the ribbon cable in. The spudger made getting the connection together easier. The Mini's battery was faster to change, but the Sad iPod is still there. The iSesamo made taking off the covers easier; my experience with the plastic tools is iffy, but the iSesamo worked like a breeze over and over.
Desoldering the battery wires from the Nano really needed a vice to hold the board so it wouldn't move. I had to use my 7-year old's hands instead.
iSesamo Opening Tool
iPod mini Replacement Battery
iPod nano Gen 2 Replacement Battery