How do I reset my Technics piano?
According to info from the below video, with the DP off, you factory reset by pressing and holding the buttons Metronome 1, 2 & 3 while powering on.
How do you fix a deceased key on a Yamaha keyboard?
How do you reset a Yamaha PSR E333?
Factory Reset:
To restoring Yamaha PSR E333 to it’s factory settings, just simply power ON while simultaneously holding the Rightmost White Key on the keyboard (C7) along with the three rightmost black keys (F#6, G#6, and A#6) until “Clr” appears on the display. Warning!