MSPM0C1104: UART can't send data

Part Number: MSPM0C1104

I can send data normally with EVB's UART0, but I can't send data normally on our hardware, the hardware PA17 PA18 has been disconnected from other circuits, what is causing this problem?PA18 is low.
Using JLIN to burn the program, if PA19 is used as a normal IO port, does the 1104 chip support burning with serial port, and what specific software do I need to use?