25 - 45 Minuten
The battery in the Nano I found was dead. I guess that's why it was thrown out.
The repair was relatively easy and straightforward. Getting the case open is tricky, especially as the plastic tool provided doesn't hold up too well against the Nano's metal backing. But the instructions were easy to follow, so things went well.
Watch out for those ribbon cables--they're easy to disconnect by accident when reassembling the case. I got everything back together the first time only to find that I had no LCD display (but I knew the Nano was active when I synced). Also, watch out not to solder the battery leads too close--they're just the right length to stretch from the battery opening to the power connection.