HDMI Problems and another...
Don't Forget that is Linux!
The HDMI or another Problem occur always because some don't do they Job enough good
Before you flash with any image try concern "what you need and what this image give you".
When somebary have rebuild a better image maybe he don't up all future for all chipset. Some of them they just need to reactivate -another need special drivers, because exactly of this new image.
If you a "flashing man" better not forget do save you last jobs(settings, favorite for ex.)
I suggest to do some test with you A/V settings, Dig. Audio & SCART -if always works -than wait:
-remember for last time -
do not RESET You Box to Default all! If so, I suggest to rebuild all video base driver to your originals + original boot-loader.
At last, if you have Linux-knowledge enough -you don't need to flash any time when occur problem.
Good Luck