Thanks to @Rose O. we have a new browser-based CPS.
https://grid.radio/opengd77
There are on-site instructions to install the FW & the donor file. You just have to plug your radio in and download https://zadig.akeo.ie/ (Zadig makes the USB connection visible to the browser)
If something goes wrong, you can alternatively install the firmware in the old way; instructions are on this forum.