I have just purchased and received a Sylphyo for a reduced price. (It's a B-stock article: the previous purchaser returned it, the packaging was damaged and there was no 5V adapter for charging it. I thought it would be a good deal.)
Earlier today, I played it for an hour or so, then it started malfunctioning. Some keys started playing the wrong pitches. I had to turn the instrument off and on again to reset it, after which it worked OK for a while. This happened a few times. Then the display suddenly went dark and the instrument no longer started up when I switched it on.
Obviously, I thought the battery was just discharged, but even after being plugged into my 5V smartphone charger or a USB port of my laptop for several hours, the Sylphyo would no longer start up when I switched it on. It seems to be dead. :-(
Also, while it was charging (or while I thought it was charging), there was no indication on the display that it was actually charging. Is this normal?
What do you think? Is it broken, or can I somehow bring it back to life?
I think I have to return it to the store for a refund, but maybe you know another option.
All help will be greatly appreciated.