How do I use this thing?

I've been working at this for four hours, looking at tutorials and posts, but there's always an m400 error. I sliced the file, and exported it onto a usb stick and everything, but nothing will work. I filled the printer with the resin already l, but I really don't know what to do at this point. I've tried every single source and tipbI could find, but nothing is working... Could someone help me out?