compile and install sunxi-tools
(optional) add udev rule to allow access to USB devices to users belonging to (previously created) "sunxi-fel" group:
SUBSYSTEMS=="usb", ATTR{idVendor}=="1f3a", ATTR{idProduct}=="efe8", GROUP="sunxi-fel"download Zadig
connect board in FEL mode to your PC
launch "Zadig"
check "Options\List all devices"
select device with VID=1F3A and PID=EFE8 (i.e. USB Device(VID_1f3a_PID_efe8))
install "WinUSB" driver (tested on Win8.1 x86)
If eMMC is not detected, SD card will be exported instead
Some boards (like Orange Pi PC Plus) which don't have FEL button require using special SD image to enter FEL mode:
Use dd, Rufus or Etcher to flash fel-sdboot.img to SD card like any OS image and use this card to boot the board in FEL mode.