The modules have to be installed, its no big deal.
I suggested the motherboard because many, many people have used this ROM (including me, I ve flashed it on several different units) and not one person has reported this problem, you said you have a new SoM and it happened again, so I think this points to the motherboard (the ROM and SoM having been eliminated).
Or its some other unknown problem. If it was just a blank screen I could suggest its an MCU issue and maybe
@dsa8310's MCU fooling trick has failed meaning the screen is blank.