Joe Sackadonut's flushed the fluid.
I see two options:
1.) Idiot who isn't able to fasten a clampshell.
2.) Idiot who doesn't know how to change cooler fluid on a 986. Maybe he also doesn't know what coolant to use.
Shurely not a thermostat problem. Cracked head is always an option.
But i think it would be more important to bring the car to somebody who knows what he's doing.
Regards, Markus