Before anything, check the air gap switch. 

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

If the air gap switch looks good, check out our general wiring guide for Zooz Ver 2.0 switches. If you have the switch 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 illustrations. 

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 and prevent it from working correctly. It's also important to use the dimmer with dimmable bulbs. 

If your dimmer is controlling light bulbs, verify that the total wattage on load doesn't exceed the dimmer's maximum capacity. Also note that if you've removed some or all of the heatsink tabs to make it fit into a double or triple gang set up, maximum capacity will decrease. You can find more on heatsink tabs here.  

If you suspect that the type of load you've connected has damaged the switch, 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.