I did a stupid move few weeks ago that make me pain in the ass!
I would like to perform a clean Windows 10 installation by removing all partitions including annoying hidden recovery partition.
Plus, I TURNED OFF THE XHCI FUNCTION IN BIOS!
As the result, I don't have any OS to boot, nor getting into BIOS.
With this model (I'm not sure if other similar Windows tablets are the same or not), if EFI partition is missing or USB EFI bootable disk attached, tablet won't let you enter BIOS!
For sure, you can use touchscreen to control cursor. But YOU CANNOT ENTER BIOS even you can see it on the screen (by pressing volumn up and power until power up)!
OK. I cut the crap. I tried to search every forum and called up to customer care. There is not an proper answer to let you know how to reset bios (not reset the OS).
Here is the trick:
1. Power off the tablet completely (long press power button until shut down)
2. Hold down Volumn UP+ and Power key until power up.
3. You will now have the screen with <enter setup> prompt, which you cannot click it to get into BIOS.
4. Hold down Volumn UP+ and Power key until screen off and KEEP PRESSING them, until you have the screen back on with the prompt telling you BIOS is reset and ask if you would like to reset the date and time as well.
That's it. It is that simple but nobody post it online that help others.~
Hope this help you all.