I had a similar issue with a Surface Pro 3 with a faulty touch screen running Windaz, the solution was to disable the USB input device for the touch screen.
On OpenBSD, you could try using "boot -c" at boot to remove wsmouse[123] device from the kernel (see https://man.openbsd.org/config for details). If that works, it's a matter of working out how to get the kernel relink to carry that change into the relinked kernel. Someone on list worked it out, can't remember how long ago though.
