I need some help. I am a newbie and I am trying to get my Sainsamart 3018 machine to engrave. I ran the laser adjusting tests, did the focusing and the adjustments and it burned beautifully. I made my first drawing in Lightburn and it does not engrave at all. I even ran the power test and it does not engrave. In one of my tests I was able to see an slight burn. Running at 20% power as suggested. What can I do?