Hello and thanks for any help with this question...

I just took the car up to the dry cleaners, not even a mile away when I heard this weird noise coming from under the right front of the hood... At first I thought it was just a belt (which the mechanic already told me I was gonna have to replace soon) but once I got home and turned the car off, the noise - which sounded like winding - kept going... Then, it started to smell electrical. Yipes! So, I moved the car out of the garage and turned it off again, but the noise kept going. I tried to disconnect the battery, but the connections were on so tight, I couldn't get them loose - although I am sure I didn't have the right tools. Anyway, the noise eventually turned into a fast clicking sound but didn't stop for over a half hour. Finally, it just died out. I turned the car back on to see what would happen - the engine started, but I didn't leave it on long enough for the sound to start again... Can anyone tell me (prepare me) for what the heck this is??? THANKS again!