The orange indicator I added makes the key lock switch position on the OMTech 60 W laser perfectly obvious:
It is in series with the lower switch on the side panel:
Although I would have labeled those switches differently, the “Control Switch” handles the 120 VAC line voltage to the HV power supply. As you’d expect, when its light is ON, the power supply is also ON and the laser is ready to fire.
Those two pictures show the situation after I turned the laser power on a few days ago: key lock switch OFF, HV laser power supply stubbornly ON.
Whoops.
The “Control Switch” still does what it should, so I can shut the HV supply off when it’s not needed, but the key lock switch has definitely failed ON.
As far as I can tell, the moving contact bar jammed at the bottom of its travel against the terminals. Pulling the switch out of the laser jostled it enough to release the bar and it’s now at the top of its travel:
If it failed once, it’ll fail again.
OMTech’s Customer Support agrees it shouldn’t behave like that; a replacement should arrive in a few days.
The Smell of Molten Projects in the Morning 
The replacement will also be just as likely to fail. I’d want a UL Listed switch (or at least one with a UR mark). The CE mark is pretty meaningless as it is widely forged. Many like to say it really means “Chinese Export.” :-)
You should see the “universal” three-outlet power block on the back of the thing! It’ll accept plugs from around the world, with sliding shutters over the pins that broke when I (tried to) insert the water pump plug. I must conjure a replacement with USA-ian outlets after all this settles down into a routine.
Apparently, all Chinese lasers have these problems, because (just like the mini-lathes) they’re all built to the same specs using the same components from the same suppliers. The only option is to pay somewhat more for somewhat better QC before it ships or far more for a USA-ian brand carrying all the right stickers.
Ain’t killed me yet … [grin]
Looking at the specs for the OMTech 60, I see that they list the entire unit as having “CE Certification.” Yikes! It’s scary that a device with that power (Class 4?) is sold without being UL Listed (or approval from other NRTLs).
Regarding it as a collection of parts generally capable of producing & guiding a laser beam seems the best approach. Anything else was not part of the design.
To be fair, it’s roughly equivalent to a low-end Lasersaur built by somebody with pretty good metalworking skillz and access to a vast assortment of generic parts.
IMO, laser cutters are about where 3D printers were a decade ago: definitely not appropriate for consumer sales, despite being sold into that market.