Diagnosis
The door uses a hinge-lock mechanism. It's not intuitive but takes 30 seconds once you know the steps.
How to Fix It
Follow this exact order:
1. Open the oven door fully.
2. Locate the small hinge locks on the left and right hinges. They are black levers.
3. Push both hinge locks UP until they click and stay in the upright (locked) position.
4. Firmly close the oven door about halfway, then lift the entire door straight up and off the hinges.
If That Didn't Work
If the locks won't push up, the door might be putting pressure on them. Open it fully, support its weight with one hand, then try pushing the locks up with the other.
Heads Up
When reinstalling, align the hinge slots and lower the door onto them BEFORE flipping the hinge locks back down. The door is heavy and awkward—have a helper.