One of the cells in the battery is gone. open and change it.
There are no skews under the rubber feet.
You need to open it, first pop up the decorative sides. unscrew the bolts from the wide speaker side, not from the side that are 2 speakers. There are 4 clips up and down on the metal cover. There are 8 more skews and you will have access. The battery is 2000mah 7.4v on single connector. replace cells or single cell in my case and it works again.
It is surprisingly reparable.
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