How to get back to the Linux Mint install ISO after installation

[Jethro]

I installed Linux Mint 21 in a TrueNAS VM, which is working well. Now I want to boot the installation ISO image in the same VM so that I can make an offline change to the installed system. I can get to the TrueNAS UEFI menu. But even if I change the boot order, it still boots the installed system. What am I missing?

Thanks.

 

[homer27081990]

Is it CORE or SCALE? If its CORE, you need to go to the devices tab and change the order numbers. Lowest boots first.