I apologize if you think that we thought that you are stupid.... That isn't the case bro. sometimes starting with the basics will lead the the root of the issue. ok you were 3 hours into the riding I see that , if there isn't a skid plate under the quad have you checked to see if the drain plug is still there? I have seen guys drag them off trail riding. Or your resovior didn't by chance get a hole knocked in it?Either way you have more than siezed the engine. the only way to know is to remove the plug and try to shine a light in the hole to inspect the cylinder wall, this is alot quicker than removing the head.