I’m sorry to hear your ZBMS3 did not come with any documentation. We do have the documents in pdf form on the website, however, for you to browse – https://smartenit.com/product/zbms3
Here’s the quick start guide for convenience – http://sandbox.smartenit.com/downloads/ZBMS3_Quick-Start.pdf
The device is an end device and will go to sleep periodically to conserve battery, but even when plugged in still operates the same way. If you can configure reports to happen more frequently, it will wake up the device more often.
I hope that helps.