Preheat oven to 425°F (218°C). Line a baking sheet with parchment paper. Place frozen burgers on a baking sheet, place on middle rack in oven and heat for 20-25 minutes, turning once, until heated through.
Place frozen chicken burgers on a microwave safe plate in centre of microwave. Heat on HIGH (100% power) for 2 minutes, flip burgers and rotate place if necessary. Heat on HIGH for an additional 2 minutes, until heated through. Thaw unopened BBQ sauce packet in warm tap water prior to cooking. Brush BBQ sauce on burgers throughout cook process using desired amount.
Preheat grill to MEDIUM HEAT. Place frozen chicken burgers directly on the grill and heat for 5-7 minutes per side, until heated through.