We had not used the device for a year or so due to covid. It would not charge, or turn on without the lead connected. I opened it up by removing the 2 screws under the rear label. The battery measured only 0.8 volts so was presumably too low to charge. I charged it up to 3.5V from an external supply. It then booted fine but came up with the contact support message.
I suspect that once you take the back off the little switch mechanism activates and bricks the unit. Dropping it can also trigger this. Seems unfair.