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?

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.