I'm trying to engrave powder coated tumblers and haven't had any luck. I've tried on a Yeti and generic ones. I've used every setting from YouTube and Facebook groups. It won't even burn the surface. Even after multiple passes, there is barely a burn mark. These are the settings I have tried for the F1:

Blue light: 100% power, tried 80-400 speed, 120-300 lpcm

Any suggestions?