Depending on the device, the serial number can be located in several different locations. Here are a few different locations...
1. Check for "SN" on the circuit board.
2. If you are dealing with a security panel, you can normally find this information under an "Info" or "About" area on the system. following the instructions below...
Enter your "Master Code"
Scroll down and locate "IMEI/MEID". This is the serial number for the panel.
Note: The serial number can sometimes be found on a sticker on the original package or the back of the device.