So not sure who this might help but I found that you can indeed force a downgrade on the Bird's firmware. Maybe this might help someone with a bricked bird.
Put FW 1.5 on your SD card, Press and hold the Sync button before turning the bird on. Turn the Bird on while still holding the Sync button for at least 10 seconds. You will here the usual FW upgrade beeps and the gimbal light will flash Red/Green. After about 10-15 mins, upgrade/downgrade will be completed and the gimbals light will stay Green and you will get a different beeping telling you that it has finished. Look at the contents of the SD card for proof.
(After 1.6.8 update) Phantom 3S Weak RC signal problem SOLVED!!!
Post #23 is where I did it.
========== 2014.01.01 00:00:14 remo-con disconnect======
Packet: P3C_FW_V01.05.0070.bin
Upgrading ...
Result: Success.
Put FW 1.5 on your SD card, Press and hold the Sync button before turning the bird on. Turn the Bird on while still holding the Sync button for at least 10 seconds. You will here the usual FW upgrade beeps and the gimbal light will flash Red/Green. After about 10-15 mins, upgrade/downgrade will be completed and the gimbals light will stay Green and you will get a different beeping telling you that it has finished. Look at the contents of the SD card for proof.
(After 1.6.8 update) Phantom 3S Weak RC signal problem SOLVED!!!
Post #23 is where I did it.
========== 2014.01.01 00:00:14 remo-con disconnect======
Packet: P3C_FW_V01.05.0070.bin
Upgrading ...
Result: Success.