The hatch has been troublesome from the get go on this car.  The handle or mechanism has been progressively getting worse the last couple of years. It has finally gotten to the point where it wont open.  Before I try to figure out how to fix it, are there any tips on how I may get it open to work on it? Can I access the opening mechanism from inside the car?

Yes, just climb in from the back seat & pull the tailgate trim off.

Check for broken piece lodged in the locking mechanism. I had this happen to a Toyota wagon I own. Couldn't figure it out till we took the catch out & turned it upside down & a piece fell out.

 

Other than that, just sounds like it's gummed up over the years. Give it a good lube.

Sweet,  I'll give it a whirl when I get a chance.  Hopefully it's just gummed up pieces..