The USB files for 2.6 are not being seen as a firmware upgrade on the 3.0 AV console. I'd like to downgrade to see if 2.6 is more fluid, but perhaps this console fits the description found in the release notes...
In the release notes it says, "Due to a hardware change, consoles that shipped with v1.1.2 installed are not able to be downgraded to prior versions. Attempts to do so will result in an error. This is expected behavior."
The USB firmware file for v2.6 should look pretty similar to the one for v3.0.0:
Either would need to be located on the root of a FAT32-formatted thumbdrive. If you can see one on your ColorSource, you should be able to see the other.
Be sure to be checking in Setup > Files > Advanced > Update Firmware