for factory reset try this (I found somehere on this site):
Press FX Unit 1B and 2B switches at the same time to enter the setup menu. Press the Model Select knob until the display reads MIDI Gate Display across the top. Turn the Model Select knob until the corresponding display shows RST FACT. Press and hold the TAP button just before (split second) pressing the Model Select knob. Its like pressing them down at the same time, but making sure the TAP button is pressed first. Do that once again to reset the M9.