As I said a while back with a serious thrust anomaly (even if for some reason not immediately noticed) the F35 would likely eject the pilot - as designed to - as soon as the 'wheels off the ground flag' switched the protections onto the 'low altitude, can't fly or hover' page.
It is curious that such a smart jet couldn't refuse or abort the take-off and save HMG a few quid but I'm sure they will have fished it out and filled it with dry rice shortly . .