Wouldn’t be surprised if it had to come completely apart, most wall ovens are like that regardless of brand. The problem is the hidden elements are more important to make the ovens look nicer, but you pay the price when they actually need serviced.
From what I can see it seems nightmarish to service there probably is no hidden easy way. Things aren’t designed to be serviced anymore.
There was a time when all you had to do was “turn” (also unscrew) “push” or “pull” and it was done; Then came the gluing and then the disassembly, called “destructive”, where a component (panel or other) are destroyed (and then replaced) to get to change the internal elements. If you send detailed photos maybe you can find the person who can help you.
In the meantime, if you have the list and the cost of spare parts, see if there is a panel (for the bottom, or back) that costs little, maybe it is the one they destroy to open it.