Metal can cause sparks, electrical arcing, and potentially damage the microwave or even pose a safety hazard.
In your case, since the handle of the metal coffee pot touched the black pattern panel and caused it to melt, there might be some damage to the microwave. I would strongly advise against using it until you have it inspected and repaired by a professional.
Microwaves operate by generating microwaves that excite water molecules in the food, causing them to heat up. When metal is present, it can reflect the microwaves and create a dangerous situation. While the handle touching the black pattern panel might not directly affect the microwave's functionality, it's still crucial to have it checked by an expert to ensure there are no internal issues or safety concerns.
Contacting the manufacturer's customer support or a qualified technician would be the best course of action to assess the damage and determine if your microwave is safe to use.