Have the same problem on my VI10 Plus it seems.
Been working fine for a month more or less. Powered it off yesturday with 80% battery unplugged (to save the battery since it seems to drag a bit connected to the keyboard in standby)
Today it wont power on. Tried more or less everything. It wont even turn on the LED when I try to charge it.
Tried loading it for 30 min with my Blitzwolf charger and a branded type-C cable, still no led, and still unable to power it on.
Tried the tricks above holding the power button and volume buttons in all kind of combination.
Still nothing, has anyone got it to work without having to open the tablet (in case I wanna return it to GB)