My switch won’t connect to my tv

This sounds like it could be an issue with one of two things. Since we know the dock works with another switch it's most likely the charge port or an issue with the motherboard.

Although the USB C port on the bottom is responsible for both charging the Switch and outputting the display, it is possible that it might be able to do one, but not the other. Have a look into the port with a flashlight and make sure there is no debris, and all the pins on the port seem straight. If there are any that are bent, they can be straightened with something thin, and non conductive. A toothpick might work, though you might need to shave some of it off so it will fit in the port. Just avoid using anything metal for this operation without disconnecting the battery first.

If not the port, then likely the USB/Displayport chip which is responsible for video output. On the attached image, it is the chip outlined in red. It is one of the more common faults with the board.