BOSS GE7 problem on shut off

[Teleman55]

The pedal functions fine when on, either with battery or power supply,but when I shut it off it does a slow distorted fadeout and no signal passes through at all.I am Baffeled and need help.

[Jazz P Bass]

Boss GE7 Schematic

I have attached the schematic.
This unit, like an awful lot of pedals, is not a true bypass when it is "off".
The switch is labeled at the lower right.
It goes into that x circuit which is a set\ reset flip flop.
This turns Q4 & Q5 on & off. (FET's)
In bypass mode, Q5 must pass the signal & Q4 must block it.
Monitor the outputs of each and I think you may find which one is misbehaving.