In this case there are no chips and only one power rail, which goes through a pot and fixed resistor to become the MasterPower voltage, so you need to adapt the above advice as appropriate.
If there is NO sound (all the switches are on, yes?) then that limits what could be wrong because mostly each oscillator is entirely separate from the others, all they share is MasterPower and the Mix output. So if nothing’s working it’s probably either MasterPower isn’t there, or there’s a problem with the output capacitor, resistor, and jack.
Do any LEDs light up?