First, check the air gap switch. 

This is the small switch underneath the toggle. It's an additional safety feature that cuts power to the dimmer when you're changing bulbs. When flipped to the right, power is disabled and this may mimic a dead device. If flipped to the left, power should be enabled. 

If the air gap switch is in the correct position, check out our general wiring guide for Zooz Ver 2.0 switches. If you have the dimmer installed in a multi-point set-up like a 3-way, 4-way, or 5-way, make sure to refer to the relevant diagrams and try to compare your wiring to that shown in the diagrams.

Also, check that the dimmer is connected to a compatible load. Zooz switches aren't rated for motor loads like ceiling fans, as detailed here. Improper loads like fans,  home appliances, and ballast tubes may damage the dimmer immediately or over time. It's also important to use the dimmer with dimmable bulbs. 

Also verify that the total wattage on load doesn't exceed the dimmer's maximum capacity. And if you've removed some or all of the heatsink tabs to make it fit into a double or triple gang set up, the maximum wattage will decrease. You can find more on heatsink tabs here, and check that the dimmer hasn't been overloaded given the wattage and number of heatsink tabs. 

If you suspect that the type of load you've connected has damaged the dimmer, let us know. And if you're still unable to locate the source of the problem, then take some pictures of all the boxes in the installation according to the angle and instructions shown here. Then reach out to us with the images so we can try to troubleshoot the installation remotely.