Its possible the alarm system is not allowing the motor to crank. If the battery is charged lock the vehicle with the remote then unlock it so all the doors unlock, you may have to press the button twice, then try to start the engine. Usually with GM vehicles the alarm will stop when you put the key into the ignition but maybe this one is different.
Its interesting that you said that it was detailed I wonder if water got into some electrical component if that is the case it might have to be replaced.
Does it have an aftermarket alarm system?
Source: vw with aftermarket alarm system, and a friends gmc sierra2004.