Hi I have a 2003 Chevy blazer. It will open sometimes. But not all the time. I hear the motor working. It will only open with buttom on the dash. I bought the blazer from a old couple who didn't open it at all. Thank you for your time and help.

 

I would suggest swapping out the hatch button and regreacing the hatch components. If they never used it then it could be roted out from lack of use.