Code P00ac, P00ca cranks will not start?

Just replaced the ecm and had a GM dealer program it, though it still had a check engine light on it started and drove fine home then took it to the auto parts store and put a code reader on it which came up with the camshaft sensor, crankshaft sensor, and p00ac which is the fuel pressure regulator something high voltage then when I was getting ready to go back home the car almost didn’t start and on the way home it was shuddering really bad like it was going to die, I got home, shut it off, and then tried starting it again it wouldn’t start, I replaced the camshaft and crankshaft sensors with GM certified replacement parts after I did that the car would not start, I am not sure what to do about the fuel pressure regulator or the p00ac code, do I need to replace the fuel pump or is it something else that I need to check out or replace first?

It was code P00CA not p00ac sorry

My Malibu first of all started out displaying “ reduced engine power “ it would drive fine until I would get on the gas pedal a little hard, I was going through my fuses under the hood and noticed a burnt wire smell but couldn’t find the source when I tried starting the car it would just turn over so I tried again and suddenly did nothing at all, I did find that the burnt wire smell was coming from the ecm so I had it replaced and programmed by a GM dealership after I took it back home it ran fine but then it started rumbling and about to stall, I shut it off but now it won’t start again just turns over, I scanned it and came up 3 codes the first two I replaced with GM certified parts which was the camshaft and crankshaft position sensors the 3rd code was P00CA which is the Fuel pressure regulator High control circuit High voltage, my question is do I need to replace the fuel pump or is there something else I should check into first besides checking the wiring?

Could you send more pics of how to get to the sensor like how to remove certain parts?

Like the intake manifold.

I figured it out but after I got everything put back together and even put in a new battery, I tried starting the car and all it did was just turn over, I waited a few minutes and tried it again and now it doesn’t even turn over, the battery is completely charged, I’m at a loss here and about ready to roll the thing off a cliff, any suggestions? Also is there a fuel pressure regulator or is that the same as the sensor?

No security light just the check engine light and reduce power. I push the start button and it does nothing, dash light, screen and everything else comes on.

Do I have a faulty ECM, is there a way to check it? It was just replaced.