Hello there nickinuse,   Have you tried using RUFUS (or similar) to transfer the iso to a pendrive and boot from USB?   Basically the platform specific bootable iso is a local repository created with Dell Repository Manager. You can create your own with the application. So why don't you try this? You can use Support for Dell EMC Repository Manager (DRM), download the application and create your own repository.   This is an option. Another options is to use Dell EMC Server Update Utility (SUU) here the Guide and Download. SUU is not bootable, you can run in on the OS (support Windows and Linux).   Hope this helps.   Regards.  
I booted it though idrac virtual console, mounting the iso as virtual media, I can see the grub menu and penguin logo, but then just black screen. I tried using grub interactive mode to remove the "quiet" parameter, I did see some additional boot messages after that but nothing seems unusual. Those were several dusty R720xd servers and I'm trying to get them back to work, firmware on them were really old, I've updated idrac(with lifecycle controller) firmware and system bios to the current version(2.63 and 2.9 respectively) individually through idrac, then I tried to upgrade the rest of them through the iso, but unfortunately no luck so far, I've ran the iso on three of them and they suffer from the exact same issue. OS installed on them(Proxmox VE) works just fine though. Update through lifecycle controller from a network repository is not applicable since they had "untested" module in the NIC, this can be overridden on Linux but not in lifecycle controller. Update through idrac from a network repository is also not applicable since idrac is in a separated vlan where I can't setup an update repository and does not allow outgoing internet connections. It seems like there is no option to update using a repository on virtual media, correct me if I'm wrong Well certainly I should try to do something about the network situations, but it will involve communications to another department which might complicate things, I really hope I can get the iso update method to work. Also there're some strange minor issues with idrac, like the first page after login will stuck at the rotating circle indefinitely, specifically the "overview -> server -> properties -> summary" page, but the "details" and "system inventory" tab in the same page works fine and the virtual console works, also a few strings in some pages shows up differently like using underscores instead of spaces to separate words, some even just show up as "undefined".   Thanks.
R720xd platform specific bootable iso boots but black screen