Not that quickly, with three other rotors on the side still lifting. There would probably be time to land safely, if not very levelly. (Also assuming he isn't flying this up to significant heights, or course).
It barely flying on all 8 rotors and center of masses is too high so stability is not about this thing. It's scare to even look at this. P.S. And I'm actually helicopters design engineer ;)
And don't disesteemed batteries, if you had never seen an industrial battries.
One rotor occasionally stops and it'll tilt down in a millisecond.
P.S. And I'm actually helicopters design engineer ;)