Yeah, yeah, ForeFlight (uAvionix cough cough) will not let you up/downgrade your Sentry firmware as you please.
That’s ok, uncle Dimme is here to the rescue!
Btw don’t ever use any of these files for any reason. I don’t take any responsibility etc etc… No seriously, I don’t.
PS: Hey! Don’t blame me for the filenames. Blame Alonzo!