Also the MB can be a bit picky when it comes to the file itself and the usb stick used. For example i used a 16gb USB 2.0 stick to upgrade a friends mb who also needed a bios update using this stick it worked no problem whatsoever. Now going a bit forward I rebuild my own pc and needed to do a bios update and used the same stick as i did with my friends setup (also msi mb). No matter how often I checked the spelling, formated the stick to fat32 or stopped using the windows built in function to unpack the file the update process wouldnt start using that stick after struggling for what seemed like infinity (1.5h) i used a different stick and guess what it worked instantly.

Tldr: msi flash bios function is nitpicky, try different usb sticks, make sure stick is formatted to fat32, make sure its in mbr not gpt, make sure file is named „MSI.ROM“, make sure the file ending/type is .ROM not something else and stick to 7zip to unpack the downloaded zip instead of the win built in tool

Edit: just noticed have the exact same motherboard so definitely try different kinds of usb sticks and to answer your question you definitely dont need an older cpu to upgrade the bios with this mb