dont use 91% find some 98% or higher. what you have isnt strong enough sadly. give 98% a try and that should kill a little more of the corrosion. or even better if you have an ultrasonic cleaner chuck it in that. look online for what u need to do for that. they are pretty cheap to get. but not really worth it for an iphone 6
put the phone in download mode and reinstall the firmware via odin. that will wipe the firmware and be factory reset. it that doesnt work your last chance would be to give it a bang on your hand a few times or the screen connector may have gotten loose.