So, I finally found a way to do this.  I ended up downloading the Windows executable for the BIOS upgrade to 6.6.0 from the Dell web site.I chose the non-packaged version R610-060600C.exe that is meant to be loaded from a Dos bootable flash drive. Then I used an old version of Rufus on an equally old Windows 7 machine on a small flash drive as this was the only way to get Rufus to give me the format that I needed.  After creating the bootable flash drive, I copied the .exe file onto it and was able to do a BIOS update on both my R610's.   The article I used was: [URL]  
I have a PowerEdge R610 rack mount that I'm trying to upgrade the BIOS from 6.4.0 to 6.6.0. This server is running VMware ESXi as the OS. I finally found an article about getting into the ESXi OS level and running the ./ xxxx.BIN command and it attempts to do the upgrade, but fails with not enough contiguous memory. Rebooting didn't fix the issue. I found an article by a VMware person about using the Dell Update Repository Manager and I've downloaded that and attempted to use it.  However, when I get to the screen where I can select my server, R610 is NOT in the list...what???     This should be so simple; all I want to do is update the BIOS.  Does anyone have any thoughts on this?   Thanx...
trying to update BIOS on PE R610 - frustrated