Suddenly stopped turning on

I have been using the soldering iron today, set it down for 1h, came back... and now it won't light up when plugged in. The web interface does not find it. I don't get an USB device plugged in sound (should it even do that?).

Any ideas on how to narrow down the error?

It is about 2 years old. I used it maybe 20 times since then.
I tried multiple power supplies but nothing seems to help.

Does anyone have any more trouble shooting tipps?