I just bought the blazer knowing it had 4x4 issues. My main issue is that the buttons don't light up at all and that the 4x4 isn't activating. So far it's not the fuse on the inside of the vehicle. I ruled that out so far. Any ideas?

 

I would try and see if there's power to the buttons on the dash, or change the buttons themselves. They tend to die due to crappy soldering

 

From what you said, it sounds like it could be electrical.

But also check the vacuum hoses while you are at it. The vacuum system drives both the HVAC acutators and the front axle engagement.

 

See if you have power to the encoder motor