ok, some new info which might just validate my theory.
i just got back one of the consoles with the 3red lights error. its an ms25 drive.
it was originally flashed using normal method from usb drive with ixtreme 1.3.
remember that when doing a ms25, the hacked firmware gets changed to ms28...?why is that anyway ??
...and hacked.bin was then spoofed back to an ms25 (since that was the original version). 2 weeks later, ring of death...ok.
ok, first things first. i dismantled this console and power up. 3red lights right away, ok.
now I powered down again and removed the sata plug from the back of teh drive and powered on again...
...NO RED LIGHTS this time...ok...mnnn dvd drive causing 3 red lights i suspect...?
So, i reflashed the orig.bin back on and rebooted console, hey presto! back in action again.
since i got that far, i reflashed again with the hacked.bin (this time using iprep usb pen and WITHOUT spoofing it back to ms25 , as yet again when using iprep the orig.bin ends up as an ms28...why

)
so anyway, this drive is working again with whats reported as being ms28 hacked.bin.
so this really backs up my theory. i would love to hear from anyone who can test this out on their console.
i would also like someone to clarify if it is or isnt necessary for the hacked.bin (made from an ms25 that gets changed during the process to ms28) to be spoofed back to ms25 before flashing back to the drive.....?
comments please....
1) Don't worry about spoofing the sammys. Sometimes refurbs come out as an ms28, but still say ms25 on the dvd-drive. Check the orig f/w itself to make sure it's the same ver.
2) If the error *is* DVD related, you will only get 1 red light, and not 3. You will also see a black screen with text in numerous languages telling you to contact support, and a 2 digit number is displayed at the bottom of the screen.
T8 & T10 bits to open the case.
All in all, you're looking at about $10 in materials per-xbox that needs to be fixed. Charge whatever you want for your work; Most people do $50 for RROD fixes, and most people pay it without complaining (if you've got no warranty, $50 is a small price to pay to get your box back up and running).