Diagnosis
The LED light bulb has burned out. It's a proprietary component, not a standard bulb.
How to Fix It
You need to replace the light assembly. Unplug the oven. The light is housed behind a clear lens on the right interior wall. Access is from the front. You may need to remove the right side interior panel by taking out screws from inside the cooking chamber. Disconnect the wire harness and swap the assembly.
If That Didn't Work
If a new light assembly doesn't work, check the wiring harness connection to the main control board for damage. A break in the wire from the door hinge area is possible.
Heads Up
The light is only rated for a certain number of on/off cycles. Avoid turning it on and off constantly during a cook cycle to extend its life.