2003 Chevrolet Trailblazer code 1275 an1280

Your original problem was probably because the security system engaged. But since you've replaced all those parts you now need a local pro with a good scanner to program security into ecm and ignition switch before it will start. These all have to match up before anything especially ignition switch and ecm are replaced. All vehicles since about 1997 or so have had security systems installed to stop vehicle theft and they occasionally screw up or when a battery is run down or replaced causes the same thing. But having it programmed now is the only option to get it running. Oh and make sure you tell the mechanic what you have replaced so he'll know

Sorry forgot about the codes both of those refer to accelerator pedal circuits. But get it running first then reset the codes and see if they come back