Even if it does not look like it is charging and even though it may be fully charged charge it using a different wall outlet than you normally do (a different room is best) for at least 10 minutes.
Do not skip that even if it is fully charged from you already plugging it in, it is important to do it, it is more for a reset than a charge.
It sounds like the firmware may be frozen try this and let me know the results hold the power switch for at least 60 seconds.
Try this at least 6 times.
The firmware can sometimes get frozen the same way that a computer will occasionally.
There is no power switch. Opening and closing the fabric cover should switch on. Is this sufficient for your trial?
Sorry, my previous remark about a charging light is incorrect. There is no light. The state of charge is shown on screen, but only when the screen can be seen !
Now working perfectly. Many thanks.