2007 NWBS EXT CAB Silverado z-71 4.8L 63k miles

Ok so this morning i stopped as usual to get my coffee. Came out and went to crank truck and it wouldnt turn over on first try. Did it again and it started up but i noticed my clock on radio went back to 12:00 like the battery had just been reset. Pulled into work, shut truck off, and opened doors -- dome lights did not come on but my radio lights were still on with the door open and key out. I shut the door and attempted to lock with the key fob. Nothing. Opened door and tried hitting the lock button - nothing. Radio lights still on. Put key in the ignition to try and start - nothing but the radio lights went out. I went into work, confused. Came out this afternoon and tried jumping it - nothing. Battery is three months old and was AC DELCO top of the line whatever it was. Before I disconnected both terminals I felt the negative terminal and it was hot. I went under the truck and and disconnected the ground to the frame and cleaned it. Disconnected ground to the engine block and brushed it off and put it back on. Put the positive terminal to the battery back on and then the negative terminal. Horn started going off. Put the key in the ignition and it started -- all electrical was working. I let it run for about 15minutes and shut it off. Went to turn it back on and it was dead. No lights, no chimes, no nothing. Repeated the steps i did earlier to get it to start. Nothing. I checked some fuses and they all looked fine. Pulled some relays but i dont know how to tell if one of them is bad. Could this be a faulty ignition start switch? Any advice or help would be greatly appreciated! I have never come across something like this! Ive never had ANY problems what so ever! The truck has no power and i cant pull any codes. Is there a way to some how get power where i can check a code?