How to adjust VADJ value in ZCU104 after PYNQ image booting

Hi all,
I am trying to adjust the voltage of the FMC connector on the ZCU104 board Version 1.0 from 1.2V to 1.8V. In the Xilinx ZCU104 User Guide, it is mentioned that the default voltage of the ZCU104 FMC connector is 1.8V. However, after booting I probe VADJ and it is 1.2V!
I have followed both of the given solutions to change VADJ to 1.8V using Xilinx SCUI software for ZCU104 or using Infineon USB005 dongle and setting Vout_command and I can confirm I can adjust the VADJ through these methods (Change FMC voltage rail (VADJ) in ZCU104). The problem is that when I switch the board to boot from the microSD card, and turn on and off the board, the VADJ voltage changes to 1.2V again and it seems that the PYNQ image is setting the VADJ when booting.
If I set the boot mode to JTAG, I can see the VADJ voltage remains at 1.8V showing that the reason should be because of the PYNQ booting.
If there any way that I can set the VADJ voltage within the PYNQ or disable it from overwriting the VADJ? In the above link, it is mentioned that there is an FSBL file that needs to be modified? Is this the right way of doing this? If yes, where is this file and how should it be modified?