Wont start...Problem?

[High Roller]

Ok owned this suv since 2004 . It has 165,000 on the clock. I went to start it and it turned over then went dark...like battery was total dead. I took battery in less than 3 years old die hard to test. Fully loaded like new. I got some sort of electrical issue. The guy at the part store told me might be a theft lock out. My theft light was making a sound while blinking sounded like my emergency flashers...strange noise.
How can I try and figure what it is or just run it into a shop. Might as well they will charge me like I did. Also my ABS went out on me I found a post on youtube to pull the fuse so it won't ware my battery down...that was 3 months ago.
Thanks much. I saw in one video could be a relay switch. 2000 XLT 5.4 Loaded.
Help

 

[High Roller]

Its a 4x4

 

[High Roller]

Ok when i close the door noise goes away on theft light. I turned my flashers on very strange sound...Its definitely electrical I got the theft warning to come on but go to start nothing..