I was trying to find a serial number for an HP (HPE) Proliant Server, and the System Management Agent wasn’t displaying the info and I didn’t have access to the iLO. I found the following workaround from a user on a forum.

Open a commands prompt and type:

wmic /node:%computername% bios get serialnumber

To find the Serial of a remote computer, type the following:

wmic /node:HOSTNAME bios get serialnumber