I tried the boot to a flashcard with nothing but firmware bin on the root method with no luck.
I am going to try DTU mode and make flash from the raspi next time I get a chance to work on it.
Discussion
Yes DTU mode should work if SD card didn't
You may need to add jumpers per board you are using, to put in flash mode.
I spent all day trying to force DFU mode with no luck. I think maybe I borked it by loading STM firmware onto a GDM chip when I first flashed from my pi3b. Need to keep digging.
I ordered an st-link to try to recover and a new mobo in case that doesn't work. Going to solder a header onto the SWD pins while I wait on shipping.
Damn, best of luck to you
I considered alternate motherboards but I can't see why. What value would I get if I'm already running a 32bit microprocessor in the stock board?
Nothing it should be fine
Is this just a creality board?