How to downgrade from Chibios to nuttx

I recently flashed my nano talon with 3.9.0beta5 and am stuck trying to connect my radios on mission planner screen, it just sits there saying getting params but never actually finishes that process. I have tried to downgrade back to 3.8.5 but am running into trouble after I have flashed with chibios I get an error when trying to downgrade.

Use QGC to flash back. It just works.