You can use JTAG to reflash the FW. I posted a rough (and tbh not super understandable, but it happens) guide on this.
I’ve just received my new FT2232HL board which will allow me to test out another potential JTAG probe. They’re very cheap from china (~$8-10) or you can spend a bit more ($15) and get the single channel version from Adafruit. Hopefully I’ll be able to edit the post as soon as I’ve tested it out.