2003 trailblazer with 5.3l v8 .... i started the vehicle my abs, parking break light and service 4whl dr light was all on i turned the vehicle off and immediately attemoted to start the vehicle again and i got absolutely nothing the radio all accessories lights everything comes on but when i try to start it wont do anything and the key is stuck in the ignition the vehicle does have an aftermarket clifford venom sst alarm system in which i do not have the remote for can the alarm lock up the vehicle so the key wont come out or start but everything comes on and what are other possible problems i may be having thanks in advance for assistance

 

also to add i tried replacing the battery and the ignition switch wont turn all the way back i had to unhook the battery

 

I'd start checking all the grounds.

 

Sounds to me like you have a problem with the ignition switch itself. Wiggle the shift lever....might not be all the way into Park