The door latch has failed. It will need to be repaired to allow the oven to operate properly.
I believe that your model is a built in type. To access the lock and its associated parts it will be necessary for you to pull it out from the wall and place it on a table or something near the cabinet it is in now.
I am searching for the servicer manual for your unit but have not been able to locate it in my archices yet. Im pretty sure i have it, but it is going to take me some time to locate it.
Thank you for your patience.