I'm also experiencing this same issue with a Dell Optiplex 780, running either the x86 or x64 builds of batocera.linux 5.20 from two different USB drives.
The latter drive runs fine on my home desktop, neither drive runs on this Dell Optiplex 780.
Have tried numerous BIOS settings to no avail, same issue is that it will display batocera.linux on boot then get stuck on a black screen, no splash is displayed.
Have also tried enabling splash sound in config and never hear it, so not likely to be a video output issue as have tried multiple monitors (using a DisplayPort -> HDMI output)
The idea to try this came from this YouTube video showing batocera.linux running on a Dell Optiplex 360