1 - 3 小时
I had to change the the battery of my iPod touch 4G because it was too old and didn't last for long time anymore
The repair was really hard. Apart from removing screws and disconnecting some components, I didn't realize that I broke the link to the volume controls, but it had been the only problem until I realized that I had to unsolder the old battery and to solder the new one, and if am really bad at soldering. I don't know what went wrong, but I ended up throwing my iDevice because after one day of work, I still couldn't make it to solder the new battery.
MY ADVICE IS TO TRY TO REPLACE THE BATTERY OF THIS IPOD TOUCH MODEL ONLY IF YOU ARE GOOD AT SOLDERING, OR YOU WILL END UP THROWING YOUR DEVICE AWAY.