For a more decorative approach using the same technique, draw a shape around the hole. Try a circle or square, or have fun and draw hearts or stars. Place a coordinating color fleece scrap larger than the drawn shape underneath the hole and secure with pins. Sew around the hole on the drawn lines using a zigzag or decorative machine stitch. Trim away the top layer of fabric inside the shape close to the stitching. Trim the patch underneath 1/4" outside the stitched shape.
Another method would be to machine embroider a design over the hole. Trim the burned portion from the hole. Hoop tear-away stabilizer and spray with temporary adhesive. Finger-press the shirt to the stabilizer, centering the hole in the hoop. Cut a fleece scrap the same size as the hole and fill in the space to prevent a dent. Attach a water-soluble stabilizer over the top with a fix-stitch or adhesive spray, and embroider.
If you use one of the last two methods, consider adding a few more strategically placed motifs so it looks like the design was planned.
