Hi,
Have you proved that it is a speaker problem and not an audio amp IC problem in the TV which is affecting the right channel?
Try connecting headphones to the headphone socket and check if the audio is OK there or not.
Can you connect an external audio receiver such as a soundbar via the HDMI-ARC port or the Optical digital audio out port to check if the audio is OK this way?
Since it is new though I suggest that you do contact TCL and get a replacement TV and keep doing this until they get it right.
You have paid for a fully working TV and haven’t got it.
If you try to repair it yourself, at this stage you will void the warranty which you may need in the future.
Don’t let the manufacturer get away with passing off faulty products. Making them honour their warranty will make them aware that customers are holding them to account for their products and hopefully it may make them improve their products or at least their quality control systems. If people don’t do this, the manufacturers will continue to go on as before, thinking everything is OK. Replacing faulty products under warranty affects their bottom line which at least makes them take notice of the problems