2003 Dodge Ram

I have a 2003 dodge ram 1500 5.7 hemi 4x4. So I was on my way to work today and my truck just turned off I mean nothing worked not even my flashers but there was a little red dot flashing. When I put my key back in the flashing stoped but stell nothing no flasahers and headlights nothing. Is this just my battery or is it my security system. I am not vary mechanicaly in clined so any help be helpful.