What is this component of a TV called?
The problem you have is not techincal one (at least so far). As Bimpelrekkie said, you must not open your TV and try to disassemble it further or fix it - you simply risk to void the warranty, and will get charged if service center finds it out.

Your problem is in business area, particularly in safety. The smell from electronics is not  a regular mode of its operation. Smell usually leads to fire and injuries. Negligence in this respect is not tolerated.

If your TV has already been brought to the service center, you must have some proof of it. The next step would be to apply to the management of the service center with written claim that your TV is a safety threat, and get their receipt that they have been notified about it.

Next step will be to apply to the local representative office of the manufacturer (Sony).

The abovementioned actions can be performed without visiting the locations, through email, with further visit on agreed time.

You may also make a shortcut writing to the social media, it may speed up the resolution if you do it properly, but may involve you into the unpleasant and negative conversations publicly.