I've not experienced the red screen as of yet, but two people I've spoken to have had this issue. I have, however, had the pause in the screen raising and the delay in it going down, but as mine is a full retrofit and I installed my MMI box almost immediately then I just put this down to my battery needing replacement (which I've still not done yet).
As for the Vendor willing to investigate, don't hold your breath, they are sellers and quite probably won't bother as it's well beyond their remit.
The red screen is that the screen isn't receiving an image, and as the MMI box is in-between the headunit and screen then the likely cause is the box, press your vendor to replace the box at the earliest opportunity, try not to let them keep offering silly ideas as to what to do as they'll just drag it out until you give up.
As for the Vendor willing to investigate, don't hold your breath, they are sellers and quite probably won't bother as it's well beyond their remit.
The red screen is that the screen isn't receiving an image, and as the MMI box is in-between the headunit and screen then the likely cause is the box, press your vendor to replace the box at the earliest opportunity, try not to let them keep offering silly ideas as to what to do as they'll just drag it out until you give up.