wasteland trek to find computer

I read this (was possibly an advance copy or a kindle free book) . The main character ( I think he was a lawman of some sort) heads off ( with a small group of people, the numbers increase as they go) to find the computer in charge, or discs....pretty sure there is an android in the group. Journey is across a vast wasteland of desert. They find the city they are looking for, abandoned as expected...concrete and steel, huge buildings...have to sneak in underground to avoid AI sentries...at some point there is a huge explosion that the group watches from one of the building. I cannot remember much else, if you can help me with title and author, I would be super thankful.
Thanks!

And found it! Deadeye by J Garrett. Hours in my gmail searching. Thanks for your attention ;-)

Thank you for answering your own question! I'm sure someone down the line will be very glad to find the answer.

Haha I like it

happened so many times to me touch wood ive remembered just before posting though