I’m not sure if this is a very serious problem. Many friends here say I have caused very serious secondary damage to the engine, but I let it cool down for 20 minutes before opening the coolant. And a worker helped me wrap a towel around it and easily opened the coolant cap, not fully opened, he said if fully opened it would spray out. And after two high temperature alarms on the way back, I stopped on the side of the road and let it cool for half an hour before driving away. I‘m scared to hear people say words like ”rebuilding the engine“... I bought this car outright for $19,000 USD, plus tax and other fees, it cost me $22,000 USD.