I recently bought a P4 pro+ from a friend who seldom used it. Attempting to fly and I noticed on the screen it needed a firmware update, I updated the controller software 1st and all seamed well. When I tried to update the firmware of the craft through the controller I get to a screen I believe is the update screen but the radio button is grayed out. I downloaded Assistant to my PC and with the craft connected I can see the craft is 2 firmware back, when I click to installed the latest version it goes through the install but says firmware install failed, tried to d’load log file but nothing. Tried to disconnect/reconnect and power through but still fails every time. Any help greatly appreciated.