Had the battery replaced in my 2004 Colorado. Now the stereo and amps will not power on. Checked fuses etc. this is an after market system. Does the anti theft control still kick in? BTW the guys at Sears auto center were of zero help. They replaced the battery.

Gosh, that was going to be my answer. Did your stereo turn on only when the ignition switch came on? If so check for a lose wire at the fuse box if it was wired into there. Follow the money, or in this case the electricity. A lot of aftermarket applications will bypass the auto's computer and anti theft system and direct wire to the battery or direct power source. If you know who did the installation, go back to them, or call the stereo's customer service to get suggestions.

Not long ago, I was driving a friends 05 Colorado when the front drivers side tire blew all of the outer tread off the tire..... Tire didn't deflate, but the tread rammed against the lower portion of the drivers side door..... Luckily because I was doing 70 on the interstate with medium to heavy traffic at the front side and rear..... I was able to safely get onto the shoulder where I intended to simply put on the doughnut spare..... I shut the engine off and looked at the wheel and figured I could at least start it back up and drive further along the shoulder to where there was more room to safely change the wheel..... Engine would not turn over at all, though all lights worked. Didn't try the radio, but all of the dash lights were sufficiently bright to indicate that there shouldn't be a problem with a broken ground, my first guess..... Long story short, got in touch with the owner who got a ride and made arrangements for a tow to a local chevy dealer..... On a Sunday when everything was closed..... On Monday, the chevy dealer charged my friend 279 bucks for a new battery and the truck was driven back home with no problem.....I was not satisfied with the diagnosis of a defective battery and did some research..... His truck had a standard key, and did not include the dings and bells of the standard anti-theft security system..... Didn't matter that the truck didn't come with the electronic key security system.....The primary components of the system were still installed on the truck and were active..... which caused the anti-theft system to kick in when the tread hit the drivers door causing the system to "think" that someone was trying to steal the truck..... Had I had the trucks manual inside the vehicle, I could have figured out how to reset the system instead of my friend having to pay for a new battery that he "DID NOT" need..... Check this site,..... http://ricksfreeautorepairadvice.com/category/repair-topics/alarms-and-antitheft-systems/ ..... You "might" find some help with the problem..... Or at least find a path to follow to possibly find the problem and how to fix it.