How do I find the serial number of an old iMac

How can I find the serial number of an old, broken iMac?

If it was under the same apple ID as you're using now then log into your apple ID and find it under about

It won't turn on, I don't have the original packaging or receipt, and it's not listed under "manage my devices". I guess they guy at the Apple Store deleted it when they set up my new iMac.