Thanks for the info on stlink. I thought I’d boot into windows and give the official tool a try. It seems to detect the flash size correctly once Software System Reset is enabled in settings (it said 2KB with Hardware reset…). I compiled a blink sketch in PlatformIO and did a program and verify. It programmed alright, but still no blink. I then clicked on LiveUpdate and it appears the flash has made a mess of itself…
This seems to happen after the reset, and values continue to change seemingly randomly even in Lockup and Hault…