Which UART? All of them or the one that provides the USB connectivity.
Is your board recognised by the OS (which OS)?
Did you try the loopback test? What's the result?
If the board used the CH340 chip for USB communication, you probably need to install a driver for that.
How does your LCD relate to UARTs? You will have to be able to load code to test the LCD. And if the UART that is connected to the USB through the USB chip does not work, you will not be able to do so,