How to find Windows Key:
https://www.magicaljellybean.com/keyfinder/
Keys / USB external keyboard:
BIOS/UEFI Setup: Esc or Del 
Boot Menu: F7
Installation:
1. Connect to Internet and activate Windows 10 on tablet first: Mouse right-click on Start > System.
2. Download Microsoft Windows MediaCreationTool.exe
3. Create "Microsoft Windows 10 Home 32 bit" installation USB Flash Drive.
4. Copy C:\Windows\System32\DriverStore tablet folder to USB Flash Drive - It contains all drivers.
5. Charge your tablet to 100%.
6. Connect USB Flash Drive, Mouse and Keyboard to tablet. Don't disconnect mouse and keyboard, until Windows 10 and all drivers are installed.
7. Disable fast start-up: Mouse right-click on Start > Power Options > Choose what the power buttons do > Change settings that are currently unavailable > Uncheck: [  ] Turn on fast start-up (recommended) > [ Save changes ].
8. Start installation from USB Flash Drive: Start > Settings > Update & security > Recovery > Advanced start-up [ Restart now ] > Use a device >  Select your USB Flash Drive.
9. Install Windows. Touch screen will not work - use mouse and keyboard.
10. Connect to Internet and update Windows: Start > Settings > Update & security >  Windows Update.
11. Restart Windows.
12. To fix unknown devices: Mouse right-click on Start > Device Manager.

13. Install missing "Intel(R) Atom(TM) Processor I2C Controller" drivers first, then drivers for "Other devices": Mouse right-click on error-unknown device > Update Driver Software... > Browse my computer for driver software.

14. Select "DriverStore" folder with drivers in USB Flash Drive > [ Next ].

15. Repeat for all unknown devices.
16. "KMDF HID Minidriver for Touch I2C Device" may still show error after installing all drivers. Restart Windows to fix it.