Version 3.0 of the Xracer F303 flight controller no longer uses the standard SPRacing hex file "target" like previous versions did.
EDIT: As of Betaflight 3.0, you can flash directly from the Betaflight Configurator GUI. DO NOT USE THE FILE DOWNLOADED FROM FPV MODEL. It is not necessary.
1) Download the Betaflight Configurator from Chrome App Store.
2) In the Firmware Flashing tab, select XracerSPI target from the pulldown menu.
3) Select Betaflight 3.0
Flash as shown in this video.
