Hi Ben
I recommend, first, checking the
fuse in the AC connector isn't
"burned out."
It could be that the power supply is broken ( or maybe other component).
I had to replace one in a Web Presenter for a client.
The unit simply wouldn't turn on. I replaced the power supply, and the unit worked fine again.
ATTENTION: The change process requires
unsoldering the damaged power supply and soldering the new one.
Check it out this link for reference
https://blog.jamesbaber.co.uk/blackmagic-web-presenter/I hope help