I replaced the door (part #WB56X10482) to my GE profile Advantium 120 over range microwave.
1. Remove the top vent grille at top of microwave by removing the 2 screws on top nearest to front edge of microwave. Then gently tilt the top of the grille forward and lift the grille out. You will notice that the grille has 3 tabs on the bottom that sits into spaces in the microwave. After removing the grille, you may want to clean it and remove the accumulated grease.
2. After removing the grille completely, open the microwave door all the way and then lift the door completely off the 2 pins that it's sitting on. I had no problem in doing this since the grille was out of the way.
3. Put in the new door the same way by sliding the door top and bottom pin receptacles onto the 2 pins.
4. Replace the grille by seating the grille tabs on the bottom and tilt grille forward. Finish by reinstalling the 2 screws on top of the grille and you're finished.
I did not turn off the power since work did not come close to any elec wires or controls.
Hope this helps.:-)