I am most worried that your pump will break down. If you start the engine when the water pump is frozen, it is easy to damage the water pump. If the pump is broken, the symptoms you mentioned above will appear.
The pointer of the water thermometer reaches the top, indicating that the water temperature near the water temperature sensor is too high. Obviously, this shows that there is no circulation of water. Of course, the broken thermostat will also cause this phenomenon, but the thermostat is not afraid of freezing and should not be broken, and other parts are more likely to break down.
The most optimistic thing is that during the emergency repair, a certain part of the cooling system waterway has not been thawed. It won't boil again after thawing for a long time. The principle of cooling system of water-cooled engine is the same, and it is almost possible.
However, it is best to try to confirm whether the cylinder block and cylinder head of the engine are frozen and cracked. This service station will find a way, for example, to see if there is any oil-water mixture. If you can check the tightness of a sewer, it will make people more confident. I hope it's okay.