Hi @JColvin ,
I afraid the problem may comes from the short circuit between JB's VCC and GND pin ,when I tested the JB's VCC pin,maybe I accidently contacted to GND pin as well. Now I have tested several pins.When the power is on,the PWRCTL3V3 is 3.3V, while all the VCC3V3 comes out as 0.43V.Also the VCC1V8 turns out as 0V,and the VIN is about 12V.Then I tested VCC5V0 and VCC1V0,they are correct. Then I tested JA and JB's pins,both the VCC3V3 is 0.43V,GND is 0V,while other pins are about 2.08V(JA1-10,JB1-10).Do I need to test other pins?