You can find out how to set up and run your Burner using our Uuni Burner Quick Start Guide
Here are some more tips to avoid this in the future:
Maintain a consistent pellet level throughout your cook (topped up to almost the top of the Hopper)
The best position for the Pellet Slide to be in is with the bolt screwed in just past half way - this should leave approximately 3cms (1.25 inch) of space for the pellets to flow in to the Grate
After you have finished cooking, remove your pellets using the Hopper Lid and extinguish them in a large metal bucket of water (as shown in the Quick Start Guide). This will prevent Hopper Lid burning while the Uuni cools down. Alternatively, you can remove the Hopper Lid after you have finished cooking.
Please do contact firstname.lastname@example.org if you have any further questions.