We are using an alternate P-MOSFET for enabling 12V and 5V input to SoM Module’s SYS_VIN_HV & SYS_VIN_MV.
Initially, we have configured the Vgs of the MOSFET as -2.5V. We found the RDS resistance is more at this Vgs condition. Further, we have tuned the Vgs to -4.5V and the issue is resolved.
We assume the SYS_VIN_MV might not able to get sufficient current to complete flashing/booting. With the above HW modification the carrier board allows the system to flash and boot.
Thanks for the support @WayneWWW, @Trumany & @JerryChang