Replace your battery. It should be able to start the vehicle with the fan
I find it weird, too, that some Escorts have the fan that stays running
after the key is off, and others shut the fan off and keep it off when the
key is off.
I've had a 85, 86, 87, and 88 escort. The '85 and '88 escorts had fans that
came (and stayed) on with the key off. The '86 and '87 did not. (Never
boiled over either...)
The only thing with the 2 that had the fans that stayed on with the key off
is that they had autommatic transmissions, where the ones with "fan always
off" when the key is off was a stick-shift.
I have heard of Escorts with standard shift transmissions and fans that stay
on with the key off.
Hell, I don't know. I just know it's normal on some cars.
Replace that battery.