You can look inside MEMTEST.IMG with 7-zip and see it won't boot. It just has literally 2 image files. It will not boot. Also I tried it, I tried burning it from windows. I haven't tried converting it ...

I tring to make a bootable usb key for memtest86. The system I making this for is mini-pc that is diskless (no cd-rom or floppy). Memtest86 only provides images for floppies (.bin) and cd-rom (.iso).

Those who spent the 90s and early 2000s tinkering with computers will remember an encounter or two with Memtest86. They won't be good memories necessarily, because you only needed Memtest86 when ...