That’s an easy one: Laser not turning off between cuts?
Your laser won’t give you a ‘Send’ option because it doesn’t have the ability to host files in the controller. The options you see in LightBurn will vary a bit based on the hardware you have.
I’m not sure why engraving an image for you doesn’t work, but images and photos generate much more code than text or simple shapes, and will stress the communication more. Your machine is using firmware that we don’t support and have never tested with, so you’re likely to encounter problems.