Q5 Pro - Black level has permanently changed after firmware downgrade

[Dedalo1976]

I thank immediately who will give me an answer / help...

When i purchased the Q5 Pro, the firmware version installed was 1.0.8. I continued updating the official firmwares (until to 2.0.4).

All the times the detected HDMI color space has always been YCbCr422 and the picture was bright at the right point.
Q5 Pro is connected to an HD TV Samsung through an Onkyo amplifier  that identified a 10 bit signal in HDMI flow...

For several reasons I had to downgrade Q5 to old firmware 1.0.8 .
After downgrade i was surprised to note that the starting colorspace detected is RGB444 8bit (not anymore YCbCr422).

Now the videos are much darker than before

I changed color space to YCbCr422 (i tried also the others colorspaces available) without results.
I tried also change HDMI Black Level over TV without results.

I returned to 2.0.4 firmware but the starting colorspace detected is still RGB444 8bit , i try others colorspaces but the videos are always more dark.... black level is changed permanently after downgrade to 1.0.8 firmware!

I tried to connect the Q5 Pro directly to the tv and repeat all the installations (downgrade and upgrades) but the result does not change :
black level is changed permanently after downgrade to 1.0.8 firmware and the videos are more dark!

...It's like watching the effect of changing video levels from 16 - 235 to 0 - 255....

I am waiting for some explanation and solution to the problem, can someone help me?

Thank you all 

P.S. I'sorry for some error, i'm italian