Hi Al,
For boot options start the tablet and then tap and tap and .. F7 on the keyboard and then all bootable devices should appear.
I gave away my Teclast und want to buy a new one.
Teclast or Chuwi? Teclast I know and I had successfully restored a full Macrium image (Android and W10) on it! This is very important for me, because it is always difficult to find the matching original software ( even on cube-tablets download page ). If found, the hell with that extremely slow download speed from Baidu begins!
Did You ever use the USB-C by connecting a hub? I saw a Youtube movie showing mechanical problems with that connector.
P.s. My time zone is GMT +7 (Thailand)