is your SW3 set to GPIO? (GPIO Switch Bank 1, SW3)
Is your serial port configured to 2-wire? (TX and RX only)
ME9210 HRM can be confusing - GPIO-2 is not the same as GPIO.
GPIO-2 is pin 11 on module connector SW3-2 and P7-3
GPIO is pin 12 on module connector SW3-3 and P7-5
Please make sure you are looking at the right pin