I have a 2000 Ram 2500 v10. I went to work today and left my keys in the ignition but in the off position, came out at lunch time 5 hours later and started my truck up but when it started up it shut off tried starting it again and it shut right back off, then after that it simply wouldnt start again. Turns over fine but wont start, and when my key is in the on position the headlights keep on flashing and they wont stop until I unhook the terminals. Turned the key 3x and got a "P done" code. Just lookin for some info at this point? Truck ran fine prior to this incident!

 

Also I heard it might be an alarm system but when I bought the truck it did not come with and alarm button.
Thats why I believe the lights are flashing and wont stop!

 

I feel like a complete idiot but I got it figured out!
All I had to do was put the key in the door and unlock then lock it