Be glad it did what it did *QUICK*!

Sounds like it was "on" but the fan wasn't running.

There is supposed to be a thermostatic switch that turns the device off
if it overheats (usually visible just inside the air outlet).

Either the switch was defective, or hanging it with the fan absolutely
not spinning may have allowed the hot air to rise away from the
thermo-switch.
Was it perchance hung with the outlet barrel facing down?

Eather way, it was broke AND defective, always a great combination!

Dave