I have the same issue. Bought the Cable Matters adapter and the Anker adapter the 2nd time and the instructions bricked both.
I was able to get the adapter to work by installing this firmware however it only displays at 4k60hz
Knowledge Base for Cable Matters Connectivity Products
kb.cablematters.com
I HAVE GOOD NEWS
I read through a bunch of the replies on this thread and found someone who mentioned that they got it to work but only with the flash tool found on the Microsoft store. Further, when they did it, they used a regular usb C port (not even one with alt mode or with DP compatibility), and they also did it without a display connected. I figured what the hell, and literally dug my adapter out of the trash and downloaded the flash tool. Turns out, it wasn't bricked, it was just that the flash tool in the zip file couldn't recognize it, but the one on the MS store could. I flashed it with the usb c -> hdmi firmware and it worked immediately. It gave me the warning that the flash was for a different board, and I clicked continue to flash anyway like the instructions said to.
I would give this a try. Hopefully you didn't throw away your adapter after you thought it was bricked!
Summary:
VMM7100 cable matters adapter
flashed using the software from the MS store
flashed with the usb c -> hdmi firmware (NOT the dp -> hdmi firmware, that one didn't work)
flashed using standard usb c port
flashed without any display connected
now works flawlessly with M1 Pro, 4K120HZ with HDR
works flawlessly with my LG C2, AND it allows my TV to remember to stay in pc mode even after I unplug it from my MacBook. The screen even switches instantly when I open and close the lid. Couldn't be more satisfied right now.
wowzas!!!
edit: the adapter does seem to get a little hot. Anyone else's run cool, or do they all run hot?