Open the Pono Player (watch the video, the link is in the intro).

Be sure to catch / save the 1cm square felt pad that falls out. If there is one... I think it is necessary and I have a photo showing where it goes in the last step.

Disconnect the battery cable.

Take some time to remove the glue from the crevices of the shell. I used the guitar pick and tweezers.

The tear down video suggests it is "hot glue" but I don't think I will use hot glue during reassembly. I think some electronics safe RTV or nothing initially.

That is my new battery in the photo, your original one will be black.