Okay so i recently had to change the PCM on my 2013 sierra 5.3 (LC9). i ordered a pcm online from a company that used my vin number to pre program the pcm. it was supposed to be plug and play. well after the install, the vehicle doesn't start and the service theft deterrent system light is on. After some research, i found out that the key must be relearned. well i have been trying the 30 minute procedure but the security light never goes off, even after 10 minutes.. 20 minutes.. hell after 30 minutes it never goes off! So can anyone tell me what my next move should be? This is my daily driver and i'm really in a tight spot here. PLEASE HELP!!!