Triggering burn alarm while attempting to cut 3mm MDF

I have a 40W Snapmaker Ray and am trying to figure out what kind of settings to use to cut 3mm thick MDF.

I’m using light burn, and tried a material test and it made a few what look like out of focus squares:

On the last of them the burn alarm went off and I had to power cycle the Ray before it would actually power the laser again.

They looked out of focus so I slide the focus lug from one end to the other and tried some simple shapes, a small rectangle at 100mm/sec and 20% power which drew part of one side and then triggered the burn alarm. An oval at 6000mm/sec and 60% power which also triggered a burn alarm almost right away. Lastly a hexagon at 300mm/sec and 35% power which also triggered a burn alarm.

I didn’t actually notice any flame during this process, but I have an enclosure and it might just be hard to see.

What kind of settings should I expect 3mm thick MDF to need for cutting?

Oh, I also tried the Luban example ruler project and it engraved the curved measuring part, but when it got to some of the later bits where I assume it was attempting to cut it also triggered the burn alarm. However I’m not sure what power settings Luban was defaulting too.