Wont start, doesn't seem to be starter any ideas???

My truck has been a champ. Totally reliable till yesterday afternoon when I got in, turned the key and it clicked then did nothing. Dash lights worked so I assumed starter. It's an 05 so not a huge surprise, however it was unexpected so I'm not completely sure where the "click" came from. Today looking further I have 12.5V at the battery posts. Headlights don't work but marker lights do. Radio, windows and door locks are all inoperable.

Sound familiar to anyone? Any ideas where to look next? I have the battery charger on it now, but somehow doubt that's the problem.

 

its the battery

 

Battery or terminals/cables.

 

2nd