NEW WORLD TGO 70 BUILT IN GAS COOKER GRILL?

A relative was unaware that the grill door must be kept open when the grill is in use so the door was mistakenly closed when in use.
The grill gas went out also the igniter, and so the grill is now not working at all.(fuse checked ok).
The oven and hob are not affected.
Please advise what can be done to restore it back to life or what has failed.
NB.I am competant at DIY and understand that it is illegal to work with live gas if not Qualified.
Many thanks.
DAVID W.