Dell SSDSC2BB480G7R (#64TMJ) SSD firmware update on Poweredge R710 with Perc H700

Hello,

I recently installed 2x SSDSC2BB480G7R SSD drives on a PowerEdge R710.
Those drives are the certified DELL version (part number 64TMJ), not the corresponding OEM Intel S3520 drives.
The server has a PERC H700 controller, and is running Windows Server 2012 R2

The drives are perfectly seen by the H700 controller, and everything is working fine.

I'm encountering problems updating the drives firmware to DL42 (they are currently running DL41) :

I tried first with the 64 bits update package for windows downloaded here www.dell.com/.../DriversDetails :
 - It sees the drives, lists the new vs old firmware version, and ask for selecting the drives to update,
 - when clicking "yes" to continue, it ends up with a failure, displaying "The operation failed due to an invalid image file" for both drives.

I also tried to download the Nautilus A19 version listed here www.dell.com/.../DriversDetails :
 - I built the USB flash
 - In DOS BIOS after hitting F11 and choosing the USB as a boot device, it just loads the regular OS. I guess this issue is because this tool was designed to run only in UEFI mode ?
 - After setting the Boot mode to UEFI, the tool loads, but the is almost nothing on the screen. I did not capture, but I can remember seeing a "Drive" button, and almost nothing else : no drive list, no other buttons
 
Any idea on how to update the firmware in that config ?
 
Thanks !
Fred