Hi guys, i've got a strange problem i want to share with you to see if anyone could give me some pointers.

My girlfriend has an M-Reg Fiesta 1.6 Si. Now i wasnt with her at the time so i can only tell you what she told me is happening...

She was going home the other day, she got to her street, and was about to park up when her engine starting making strange noises and her battery light was on. I dont know what the noises were coz i wasnt there, but she reversed into her space, and she turned off the ignition, but the engine remained running even though she had taken the key out (meaning she could still even rev the engine!!), and the fan belt was still spinning round. The only way they could stop it was to disconnect the battery, and her dad noted at that time her battery was red hot. Since the battery light was on it almost seemed like the engine was running off the battery instead of the alternator if that makes sense?. Anyway's, I myself havnt looked at it, but she had her mechanic friend of her dads take a look and he couldnt see anything wrong. Although i dont know if he even tried reconnecting the battery or anything. He's going to get it towed to his garage so he can have a better look on Monday.

I've never seen a problem like this, have any of you guys?. I mean i know that if the battery light comes on it can usually mean the alternator is not charging the battery and its draining, but what can cause the engine to stay on after taking out the keys?.

Any help would be much appreciated!