Need to boot broken Mac-Mini using retail Snow Leopard 10.6 DVD

Hi,

In Summary:
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I have Mac Mini (late 2009) which does not boot anymore and I need to install Snow Leopard using retail DVD (version 10.6). The OS/installer from the DVD does not seem to boot either. I always very much appreciate the efforts of true geeks. So please, any casual beginner, please do not demoralize with something like "cannot be done" etc.

The complete story:
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The start of the problem:
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1. All of a sudden, one fine day, on start up, my Mac Mini strated to shut itself down without no apparent reason to me. When trying to boot, it would show a progress bar for about 5 minutes - I am assuming that was disk-consistency check being performed. My best guess is that right after the use of Carbon-Copy Cloner (but I am not 100% sure) it all strated to happen.

2. Performed Mac's Disk-Util check and [Verify Volume] used to display "invalid directory item count, should be 31 instead of 29". Surface scan said disk hardware is 100% fine. Volume Repair never worked, since OS X was installed on the primary disk. I lost the DVDs that came with this Mac Mini, so the option to boot from that DVD and launch Disk Util etc. was not possible.

TechTool Pro - No Help:
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3. Started googling and had to choose between [TechTool Pro] and [Disk Warrior], opted for TechTool Pro. Tried its bootable DVD only to learn that TechTool Pro cannot fix it. Again, it's surface scan suggested disk hardware is 100% fine. Sent the details to TechTool Pro support team, they couldn't help either after a couple of e-mails+data exchange. (How do I claim my lost money with TechTool Pro - suggestions appreciated as well).

Googling / Mac Forums:
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4. Started looking into forums, learnt that someone had successfully repaired this problem using Ubuntu 11.04 install DVD (i.e., without installing the Ubuntu, but just using its 'try from DVD' feature). I had that handy, but forgot to disable HFS+ journaling before attempting to fix the problem. Anyway, attempting volume repair that way couldn't fix the problem as well. However this step took away my ability to boot from Mac.

5. However using Ubuntu's bootable disk, I could access Mac-HDDs contents - and was able to successfully back-up *all* my important data.

6. Googled and learnt that just attempting to boot using Ubuntu DVD can take away ability to boot using Mac bootable media - possibly due to EFI internals. Suspecting EFI is now corrupt, I tried other 'hacks' like:

6.1 eEFIt Boot Disk - which does not work at all,
6.2 Empire EFI w/ Chameleon - not sure how to proceed with options presented - trying either does not work,
6.3 Super GRUB2 - boots fine, but attempting to boot from Mac-HDD fails after a couple of seconds,
6.4 Boot-132 - boots fine, prompt asks for input, but then I cannot eject/replace the DVD due to Mac-Mini (lack of) design,
6.5 Ubuntu 11.04 / 11.10 - still boots fine - just that I cannot go into Mac-OS-X from here,
6.6 TechTool Pro bootable DVD - which used to boot fine earlier stopped to boot.

As you can see, none worked successfully. So I didn't yet try other popular rescue media - as I suspect that is not the direction I need to go into.

>> Looks like most of my problems are due to the fact that I have Mac-Mini which does not allow eject/replace of DVD from command prompt / out side of Mac-OS-X.

7. Tried emptying EFI partition, playing with EFI/Mac-OS partitions boot flags, Zapping the PRAM, nothing still allows me to boot either from Mac-HDD or any Mac-Bootable-DVD.

Current State:
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8. Now while boot time, Mac displays a gray screen for a few seconds, and then a blinking prompt on black background. That's it!

Snow Leopard 10.6 Retail Install DVD:
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9. Went to Mac store and bought this DVD only to witness that I can't boot from it as well. (This is a huge shocker, how is Apple able to sell these DVDs if these don't work on genuine MacMini itself. After all we are able to boot from and install Windows/Linux on a variety of Machines).

I am hoping for a very small step/fix that I am missing, since I can still see and access all Mac-HDD contents after booting from Ubuntu bootable DVD. However I am prepared for a good amount of exercise as well - assuming someone posts a valid/verified fix.

Things available right now:
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A. Genuine Mac-Mini (Late 2009) who lost it's ability to boot either from its HDD or Mac-bootable DVDs (TechTools Pro, Mac OS X retail DVD)
Not to Forget: Mac-Mini's DVD drive cannot be ejected by any hardware button.
B. Mac OS X 10.6 Retail DVD
C. NOT AVAILABLE - DVD that came with this Mac-Mini
D. Variety of rescue DVDs, listed in section 6 above
E. Another machine/PC with Ubuntu 11.04 - giving me ability to access internet

Thanks for reading.
Zita