Why doesn't the webcam work?

Ordered a laptop cleaning with replacement of thermal paste at the nearest service to the house. I watched the process myself, I did not notice anything strange. After that, I noticed that the laptop stopped seeing webcam, tried different applications, reset SMC, did not help.

At the service, I am now ignored, probably do not want to fix.

Is there any chance that they just forgot to connect some cable and I can fix my laptop by myself?