On Windows you can try using this rescue tool to write in the firmware when it is in the bootloader mode (blinking white led). https://vflex.app/rescue the procedure is that you click begin, then select the VFLEX device from the list. This works some of the time but unfortunately we're not yet at 100%.
If this does not work, you can also:
1) plug in VFLEX (still in BL mode)
2) Open Windows device manager
3) Find vFlex in Serial Devices, right click and uninstall device
4) Find vFlex in Universal Serial Bus Devices, right click and uninstall device
5) Unplug VFLEX
6) Replug
7) Launch Chrome
8) Re-attempt https://vflex.app/rescue