Like I said, Zooz support is top notch. If they think there is any chance it is defective, they replace it for free.
update: i got the zooz 4-in-1 and the eco motion sensor and both of them worked flawlessly. took just a minute to setup. obviously some issue with the zooz zse18, either on the hardware of software side. i suspect the former, since it simply doesn’t wake up or do anything unless i’m actively poking the battery or usb. i’m sure zooz has great support, but i could care less. i just want something that works, and i can return it through amazon and move on with my life.