I found this in the forum for you SectorGZ explains firmware downgrade awhile back.
You can downgrade your firmware, but you need to download the firmware you want to go back to from here:
After unzipping the file to get to your *.DEB version you have to rename that version. So lets say you are on 3.3.02.165 and you want to go back to 03.03.01.156, do the following.
Unpack the zip file to the *.DEB file.
Rename the *.DEB file to a version number that is highr than the version you are on. Example: rename 03.03.01.156 to 3.3.02.166 to replace 3.3.02.165.
Go to your Dashboard and do a manual firmware update. This will restore the older firmware.
BEWARE : that any scripts/functions that have been changed with the firmware you are on and are not addressed with the older firmware are still the current version’s script. I would do this as a last resort in trying to find a fix elsewhere on the forum.