Alesis QuadraSynth Plus Reference Manual page 33

Connections: Chapter 3
If your footswitch seems to respond backwards (notes sustain unless the footswitch is
pressed), turn off the QuadraSynth Plus, make sure the footswitch plug is fully inserted
into the footswitch jack, then turn the power back on.
J
Don't hold downthe footswitch iwhen powering up the QuadraSynth Plus.
QuadraSynth Plus Piano Reference Manual 34