Dustin S.,   Would you clarify what specific device you are trying to update? I ask as the platform specific ISO's for the 14th generation were mostly pulled due to demoted content, as seen here. I know you were using the ISO when you used DRM, but have you tried to assemble and create the ISO just from the individual updates? If so you may want to try that path, and attempt it without using the contents of the ISO.  Another thing to consider is if you have secure boot enabled, as it isn't supported with this process.   Let me know how it goes.
I have updated the firmware & drivers our R440 & R730 PowerEdge Servers using Dell's Platform-Specific Bootable ISO with no issues, but I'm having issues when updating the R740 servers. I tried using the Dell prebuilt ISO PER740_BOOTABLE_21.12.00.24 and creating them from DRM but get the same errors. When selecting the One-shot UEFI Boot Menu and select my bootable USB. I get this error. [IMAGE] When I try selecting the BIOS Update File Explorer and select bootx64.efi file. I get this error. [IMAGE]
R740 Platform-Specific Bootable ISO Fails to Boot