1. Hot water soaking: soak the whole lunch box (if it is not metal) in hot water, or pour hot water on the lid, especially around the sealing ring. The principle of this is to expand the air in the box by heating, balance the internal and external air pressure, and thus easily open the lid.
2. Reheat: The lunch box won't open as soon as it is taken out of the microwave oven. The internal hot air cools and contracts, resulting in negative pressure. You can put the lunch box in the microwave again for a few seconds, then take it out quickly and try to open the lid while it is hot.
3, let stand and cool: the hot air in the lunch box leads to negative pressure, or you can choose to wait for the food to cool naturally for a period of time, and then try to open it after the internal and external air pressures are balanced.
Solemnly declare: The above information represents personal position and is for reference only.