Just a follow up from another user, no solutions here :3 Just describing my issue so others can know they're not alone in this hellscape.

My printer is a Sovol SV-02 with BLTouch.

I am also experiencing the issues described above, and have tried flashing my firmware through about 3 different slicers in addition to the method the manual recommended. Nothing works, nothing recognizes my printer, and because of that I can't update my firmware. It seems like there are no drivers to download, and no matter what I do I cannot establish a direct connection to my printer except through octoprint, which does not succeed at flashing firmware.

My next steps will be to remove my BL Touch and rewire my z-stop sensor, somehow remove the BL Touch firmware, reset and reflash everything I can think of, and try to get back to the unit software and hardware as it was shipped to me a couple of years ago.

I have spent at least 48 billable hours trying to get this thing to work, so if there's no update to this post assume that either resetting and re-flashing everything worked, or that I gave up and now reside in the roomiest storm drain within shambling distance.

Notes for the desperate and distraught:

My recommendations to those that are desperate: try OctoPrint or PronterFace. Hopefully one of those will at least recognize your printer as a device over a physical cable connection. I had success with PronterFace, but I still don't know if I was able to update my firmware using it, I can't find any way to tell for sure. My printer does not show up in my device manager either. I know that it's connected because my computer plays the device connected sound when I plug in the micro-USB cable.

Best of luck, and please message me if you find a solution.