Try reloading the v3 firmware before deciding to load previous version.
I loaded v3 on perfectly working beam 6hv and x5. While x5 worked as expected, 6hv developed tail twitching as if it was on a seisure. It felt if the tail was on a inteemittent contact loss. I changes the tail and it did the same thing. So i knew it was not the servo. I was going to go back to v1 but decided to load v3 one more time. It cleaned up the tail problem. It makes no sense that currupt file reported ok after the upgrade. But it worked well after it.
Beam behaved badly as if the heli had developed a vibe issue. Again, reloading solved it.