3100 overheated, are the heads cracked?

[wingman65]

My daughter's 95 Grand Prix with 3100 overheated due to all coolant leaking out at heater hose thermostat bypass, that stupid clip/o-ring design. She drove it home anyway and it overheated. I filled with coolant and when I started it coolant blew out of radiator. Are the heads cracked or can it be something else?

[SappySE107]

Blew a head gasket at least.