Nuhtles

I have a problem with my amp and sub that are currently in my car. I was putting in my new amp and disconnected the battery and main fuse then took out the old amp and hooked back up the battery (i always take off both cables negative first then positive, and then positive first then negative when i put them back on) and there was a little spark as i was putting on the negative and then there was a slight burnt smell, after that went to a friends house (main amp fuse was not installed and all amp wires were taped just to be safe) after the installation of the new amp it powered up and everything but absolutely no sound or vibrations from the sub. Any help at all would be great, ive checked all the normal stuff fuses and such im just lost on this.