Na I think that's the horn.

 

Horn is red button. That small round button on bottom right should be for rear glass release. If not that might be the remote start button.try pushing the lock button and them push that random button twice and hold second time while close to blazer.

as mentioned it might not be from factory, but I know that's one way for a remote start to start lol...

 

Somebody said these remote starts tend to cause problems and will leave you stranded so it may not be worth fixing. Maybe somebody disabled it for that reason. I sure don't need any more problems. I just thought it was cool to have. But like every thing else you don't need it until you get it.

 

I'm certain it's an aftermarket remote starter system. The sticker is similar to the ones we used with remote starter installs. It's likely that it stopped working, or the remote was lost and the previous owner went back to just using the factory remote to unlock the doors. It's also possible the previous owner had the remote starter un-installed at some point. You can look on the windshield near the rearview mirror to see if there's an antenna stuck on the glass there. Otherwise you'll need to do some investigating under the dash to find out for sure if the remote starter system is still there.