I was carrying armed quad and transmitter while opening a gate in a fence.
RTB mode. Throttle got bumped. RTB engaged. Bank angle compensation built into RTB boosted the throttle high. An issue in altitude PID2 stuff kept the throttle high, making things worse. This was a 330 quad with mild 2212kv1000 motors with flexible cheap 9 inch plastic props with rounded tips. This makes me even more afraid of carbon props and powerful, high RPM motors.
Slightly graphic descriptions of injuries:
It was 50m in the air by the time I got my bloody (literally) hands controlling it. It's not fun flying with badly lacerated hands, but I did get it back down safely. Luckily my thumbs were OK, so blood didn't get into the transmitter. It warranted getting stitches. I will avoid a description
but I have medical training so I spent an hour carefully bandaging several fingers and it healed well.
CleanFlight:
While testing an RTF CF quad (so this may not be CF defaults), I saw that issue too. Motors off, switch off the transmitter and the motors come on for a few seconds (it is a landing mode). Safety is why the default failsafe is "motors off" in LP at least.