Simpson Model la Stella Oven Thermowave not working Fan works and other settings OK

The oven is probably in auto mode, reprogram the timer for manual operation normaly symbolised by a image of a hand

https://www.google.com/search?source=hp&ei=4sN1Xo3pMseTjLsPoPmZ0AQ&q=How+do+I+remove+the+door+from+a+Simpson+La+Stella+oven&oq=How+do+I+remove+the+door+from+a+Simpson+La+Stella+oven&gs_l=psy-ab.3...33892.33892..34736...0.0..0.236.236.2-1......0....2j1..gws-wiz.4AN9HYMLmgM&ved=0ahUKEwiN4u-hh6voAhXHCWMBHaB8BkoQ4dUDCAU&uact=5#kpvalbx=_78V1XoCeDOWZlwSiq5-gBA59

check that both top and bottom elements work, if a thermowave then the element which is circular and behind the grill cover the fan

go to your authorized service agent and ask for a parts diagram for the door hinges
that will show small locks that when the door is open can be rotated into the slots of the hinges and lock the hinges open
from there you lift the door up and out of the hinge slots

I would say that the oven element has blown. It is common especially if you have a fan forced model. Make sure the fan works before you go buying a new element as the replacement will fail early. Simpson ovens have to be removed from the wall cavity to replace the fan and the element. Make sure you tuen the power off before doing anything...
Give the parts supplier your model number so that you get the fight element ( and fan) if necessary.

I have a Simpson Atlas Mira. Was having a hard time getting the glass cover off too so looked on the net for a solution. Couldn't find one so I persevered and sorted it...
The glass cover has a screw-off thread (like a glass jar) which unscrews anti-clockwise (lefty loosey). I had to give it a good few wiggles and pulls before it would start unscrewing. I also had to use a damp towel to get a proper grip - it's a slippery little bugger - but I got it in the end!
Hope this helps someone - good luck!
JD Hamilton, NZ

I don't know if this will help. For the 720ef , this is what you need to do.
There are five buttons on the clock panel and from left to right they are:- Minute Minder, Cook time, Ready Time, Plus and Minus.
TO SET THE TIME OF DAY
Press the Cook Time button and the Ready Time button simultaneously. Use the Plus and Minus buttons to set the time.(24hr clock).
TO SELECT AN ALARM TONE.
Press the Minus button to listen to the first tone. Release it and press it again to listen to the second tone etc (3 tones)
Releasing the button after the tone has sounded will automatically set that tone.
SETTING THE MINUTE MINDER.
Press the Minuter Minder button and either the Plus or Minus buttons simultaneously to set the time.
You can cancel the timer at any time by setting it back to 00.00 by using the Minus button.
After setting, the display will revert to the time of day, but by pressing the Minute Minder button again, the display will show the remaining time.
If you want all the information, then it is best if you supply a vaild email address and this will give you access to my BT Digital Vault, where you can have a complete copy of the handbook that I have scanned in.

How do i set the time on a Simpson La Scala wal oven

sounds like you have a control board problem