One should never make assumptions with troubleshooting. Parts and labor are expensive let alone credibility to the repair tech.
Let us know a bit more of what you observe with this. Like is the pilot lit? Does the fan run, does the burner go to low flame or no flame? Any actions that happened previously in the kitchen the last week? Like a deep cleaning or movement of equipment. Addition of equipment. Is the BJ thermostat bulb and capillary tube properly attached and not damaged from from pans, cleaning, or movement. Are the top burners firing correctly with all lit? (gas flow)
the pilot light is off, fan running observe that after deep cleaning found thermocouple dirty and residue of water . change thermocouple run oven found thesame . pilot light off ,burner off ,fan running. thank you guys .
You say you found water. Check to see if the oven vent is clean and clear. Water makes steam and steam is a great fire extinguisher. A tablespoon under the burner is all it takes to smother the pilot. Perhaps someone is overloading pans?