Why Doesn't the PX90 Turn ON after Pressing the Power Button?

It is a safety feature. Press and hold the power button for about four seconds to turn the test set ON or OFF.

As a safety feature, VeEX's V90-series has a delayed power button, to prevent it from being accidentally powered ON or OFF (e.g., while being transported or stored in its carrying bag).

Press and hold the power button for about four seconds, until you hear a beep, for it to take action.

For more information refer to the PX90 PON Internet Service Installer | Quick Start Guide.