I have a button on my keyless remote that says GM but it doesnt do anything, searched everywhere but cant figure out what it does!

Welcome to the forum Dalton.
Do you have a photo you can can post of this remote?
Is this for your 2000 Chev Blazer?
Your factory remote info should be listed in your owners manual, hope that helps..

Yes, didn't come with a owners manual sadly when I bought it off of a private owner so I'm not real sure if this is factory keyless remote, wouldn't let me upload a picture I dont think but if it works you'll see what I mean

Ya perfect pic. Mine does not have the GM written on mine, but it is for the trunk on my car or the lift gate glass on yours I believe.
Here is the link to your online free pdf owners manual.
http://www.vadengmpp.com/owners-manu...let-Blazer.pdf
Section 2-7 is where the FOB info is that I found...
Hope this helps!

More than likely that button is suppose to be for the rear lift gate. My 2000 Blazer remote has liftgate where that button is. I must have the high end LT Blazer vs your LS Blazer.

And no, one simply can't upgrade.

I don't know for sure, but it'* possible that'* a replacement remote, designed to be used with models of various different body configurations.