How to see if PoE HAT works or is broken

Hi all,
My Pi S works great on Armbian, but i’m having trouble with the PoE. I don’t know if the problem is the HAT, the PoE supplier, the Pi S itself (it boots from USB-C into Armbian just great). Does the HAT have any status LEDs? Can you see if it’s working with a multimeter, or power it directly from a power supply, just to test it works?

EDIT:
If you are reading this because you wonder if your PoE hat is broken, please see to confirm you are not using the PoE hat on the wrong kind of Pi S: Rock Pi S PoE HAT - doesn't seem to power anything
Having said that, knowing if a HAT is working or broken (whether you have a Pi S or not) is a separate issue, so i will leave this thread up too.