1. Download STLinkReflash (Version 190812 tested)
2. Modify the following offsets in STLinkReflash.exe
  2566 3C  38
  2567 40  C0
  26B2 3C  38
  26B3 4A  C0
3. Run STLinkReflash.exe and accept, selecting option 1.
4. Fun and profit!