Cant flash OS due to rootfs error

Flashing the vim3 from win10 using the EMMC burn tool gives the following error:

Vim3 was set to upload mode by pressing the function key 3 times.
The OS image is Linux Desktop EMMC
Tried with the new burn tool and the old one, and it gives the same error.

seems to be flashing a new board ok. something is wrong with the other board