The battery is not user replaceable. There have been no successful reports of a user replacing the battery.
I suggest you change your USB cable a few times and make sure that the wall charger supplies 1.5 amps or greater.
At the very end of the thread, Franco Melechi does indicate that he successfully used an LI-92B Olympus battery as a replacement. However, there is no followup for a low-term test. I suggest you attempt to contact him by DM before you attempt a battery replacement.
If you have success, please post a report.