I had contact with the BenQ support recently.
On my small GV1 beamer, the auto switch off timer cannot be canceled by pressing a button. So I wrote them, that this is maybe a bug.

That was the answer:

"Thank you very much for your inquiry.

Insects entering the monitor through vents are a common problem that is not covered by the manufacturer's warranty as it is not a manufacturing problem.

This problem is known to all monitor manufacturers.
The cause of the problem is usually that the monitor is used in a dark environment without a secondary light source being activated.

If the insect is still alive, you can lure it out with a light source (the monitor should be turned off and cooled down).
If the insect is dead in the monitor panel, wait until it is completely dry. Then you can carefully press on the screen, next to the insects (avoid crushing them) and it should fall into the panel and leave the visible area.

Nevertheless, please send us a picture where we see the problem you are telling us, I inform you that the picture must be less than 2 MB in size."