Cannot flash eMMC from Windows 10

[GuiPoM]

Hello !

I am currently trying to put an OS on my tinkerboard S.
Following the user manual, I have set the jumper to eMMC recovery, plugged into Windows 10 1909, Windows shows an unknow device but nothing happens, no drive found.

If I do the same set on eMMC Power on, I can quickly see two drives, then the red light switches off and the drives dissappear. 

It boots from SD card with jumper set to disabled, but I do not want to boot from SD card, I use a TinkerBoard S for its eMMC.

Would you have any advice ? 
Thanks.
Guillaume

Edit: maybe this is something I do not understand from the doc:

disabled means ... boot from SD, but eMMC storage from PC when plugged in
eMMC recovery means ... I don't now, reset ?
Power on means ... use eMMC ???

[Im4Tinker]

Better you use Linux, then you may a better chance on your attempts.
One more option is to have a USB-232 adaptor and plug it prior booting. See discussions on the forum.

[GuiPoM]

Better you use Linux, then you may a better chance on your attempts.
One more option is to have a USB-232 adaptor and plug it prior booting. See discussions on the forum.

Well ... my RPIs and Tinkerboards are the only Linux based machines I have at home ...
But I manage to get an OS flashed. I am more worried not to properly understand how the jumper works. 
I did something which looks completely different from what is documented and have it working ... which is good, in a sense. And also very strange!

[Im4Tinker]

The jumper will pose the boot loader (u-boot) to search for the eMMC.
So if the u-boot exist on the first 4 MB on the eMMC, it will start from there. If detecting an USB connection on the micro USB, it will perform as media reader.
If u-boot is not available/readable from eMMC, the last attempt it will be to search for a SD card, if present. Then it will try to find the u-boot from there.

You may find this of some interest.