May you provide more detail about the RAM, the appliance, and the Windows OS? Other than that you need to use a proper testing tool, ideally the same one used in the shop. To check RAM's SN number do the following:
“Start” or press the “Windows” key
Type in "Command Prompt in the search box. Right-click on the results
Select “Run as administrator”, enter Command Prompt in admin mode
Type "wmic memorychip get devicelocator, serialnumber" (without commas) in the window that is displayed:
Press "Enter" and you should see he serial number displayed under “Serial Number.”