Good point. I reviewed that thread, and didn't see any indication of a resolution by the OP. What happened with that?
I mentioned a potential ground / short issue back then.
Alternatives, given the additional description:
- Something is miswired on your radio harness / connections (could be as simple as mixing up the constant / power-on (+) wires - yes, you have two separate power wires (more if you have the Bose))
- Your aftermarket radio has an issue (unplugging an HDMI connection 'incorrectly'; e.g.; with the radio powered on, as an example - *might* kill that input and require either a power-off or a hard reset - but it should not affect the voltage of the product. There isn't any voltage source in an HDMI, from what I know - it carries integrated video / audio signal from one device to another. Which brings up the question - what's on the other end of the HDMI, and are there *any* wires on that device connected to the *same* source as the radio (power / ground) ? A multimeter would help, here.
BTW, can you provide the make / model of your head unit?
Did you cut wires on the vehicle side of the harness? There are wiring diagrams that can be downloaded to validate which wire does what. And some wires, while present on the vehicle side, might not be used on an aftermarket install.
Another thing that can be tested - what happens when there is *no* HDMI connection (yes, your external device won't be sending audio / video - but is the radio 'stable', if the input is not connected?)
Still further...do you have a code reader, and if so, are there any listed when the dash goes haywire? For some reason, I'm thinking that these 'additional' issues you're seeing on your dash may be due to a secondary CANBus communication issue (caused by your radio issue,
not the other way around). Just a thought.
<soapbox> Finally, although I'm not a mod here... starting multiple threads on what is essentially the same problem (especially if a resolution is not posted for the first one) - not only is bad 'form' - but all of us (including the OP) spend time chasing a problem down all over again, not leveraging the steps already taken. </soapbox>