The vProtection and iProtection both are at 0,5v measured through the vias beneath the CPU and using ground from the P9001 connector.
Of course, once over-current protect is triggered, any shorted CE transisors makes +B voltage flow to speaker terminal,
causing DC protect port voltage larger than 0. Indeed,
these protect ports ,DC or I, keep zero voltage, always.
The problem stays even with the preAmp Board removed. The above action proves you have a logical thought
and is,maybe,a good qualified tech.
I suspect the problem be either on the HDMI Board or the Amp Board, but i can not find any obvious problems.
Not related to HDMI board, check ALL POWER TRANSISTORS mounted on the large heat sink.
How to check?
On board test, using an ohm meter to test ALL CE resistances to see if they are nearly zero.
Then measure ALL CB and BE resistances and jot
them down. no more than 2 channels are shorted,
enabling you to make a comparison.
The 3 pins white resistor will open with infinity resistance
instead of 0.22 ohm. Check them ALL.
Any open resistor means transistors is blown. Left 1-2-3 right pins 1-2 0.22ohm, 2-3 0.22 ohm. In some special cases, it won‘t blow but transistor will due to a very special reason.
Don‘t tell me no any shorted power transistors.
Do 3 things:
take a photo on top. I tell you how to distinguish I or V protect with posted.
measure ALL CE,CB, & BE resistance jotting them downfor comparison.
Find out shorted one(s).
I am now playing a game no time to read lengthy composition.