Updating the firmware on the Dell EMC PowerVault ME 4 series is pretty straight forward. If you are downloading the firmware on macOS, there's a small caveat though.
The download is delivered as a ZIP-file and contains a single binary file with the extension .bin. When unpacking this ZIP file through the Finder, the BIN file also gets unpacked. In order to successfully get the BIN file, you need to unpack the file through Terminal:
Download the latest firmware from support.dell.com
Start up Terminal and navigate to the folder where you downloaded the ZIP file containing the firmware.
Unzip the ZIP file using the "unzip" command:unzip GT280R004-01-dellemc.bin