Remove two screws underneath appliance to allow display to hinge down. This allows two screw securing outer case to be removed.
Remove two screws to allow access to combustion chamber
To gain PCB access remove the 6 screws securing the front fascia. You will need to remove housing from its catch to remove the screw to the right of the pump. If you are doing live testing on the PCB you should refit the housing to its catches and refit the two screws underneath the appliance so the housing is stable.