How can I downgrade firmware?
Can you narrow down the situation a bit more?
What device (Photon, Electron, etc.) and what version are you going from and to?
And over-the-air or USB?
But if you can I’d rather do it via USB.
What ScruffR said.
Go to the release site and download:
Flash them in the reverse order using the CLI:
particle flash DEVICE_NAME_OR_ID system-part2-0.7.0-photon.bin particle flash DEVICE_NAME_OR_ID system-part1-0.7.0-photon.bin
Note that you must flash part 2, then part 1 when downgrading.