Caught in a conundrum while trying to upgrade a Mac Mini (mid 2010) from Snow Leopard to Mountain Lion

Question

Hi gang,
I am in a very frustrating position as I try to upgrade my Mac Mini (mid 2010) from OS X 10.6.8 Snow Leopard to whatever the latest version of Mountain lion is. The reason I am doing this is because the original hard drive died and the Mini sat there for 6 months before we decided to get a new hard drive and revive it.
I installed a new 500GB 7200rpm SATA drive and the problems began.
First I couldn't get Mountain Lion installed as a fresh OS installation (using both a USB drive and a DVD to no avail). It just wouldn't go. The grey Apple logo/loading screen would come up and just sit there doing nothing while the loading icon spun.
I then tried installing Snow Leopard (the OS that the Mini came with when it was new). After some messing around, that got done.
However, a peculiar thing happens when the Mini boots. Everything loads up into Snow Leopard, but although the mouse curser moves, I cannot click on anything or use the keyboard for 4-5 minutes. Then it just work (I am typing this on the Mini). This happens every time.
Now, when I updated to 10.6.8, I was able to load up the App Store and download the Mountain Lion install app. I clicked it and went through the initial copying of files and then the restart, but after the reboot, the grey loading screen would not progress. I rebooted again and held down the Option key to check out the available boot volumes, and all I saw was the installation DVD I had in there for Snow Leopard and a hard disk volume called "Mac OS X Installer."
So I booted into the Snow Leopard install DVD and opened Disk Utility to check things out. I did a verify disk and a permissions repair. Interestingly, the first repair I did gave me the message that the ACL was missing from Volumes and that is was fixed. I read something somewhere which talked about the Access Control List and mouse/keyboard issues. But who knows. When I boot back into the Mini as normal I am returned to the fully-functioning Snow Leopard installation, like nothing happened.
And now here is the kicker: it appears that the Firewire bus is hooped. In the Profiler, when I view the FireWire settings I get the message, "Warning: Unable to list FireWire devices." So I am pretty sure the one thing I cannot do is boot the Mini into target disk mode attached to my Mac Pro and installed Mountain Lion that way.
So to recap: I can't finish the Mountain Lion installation because the install won't continue after rebooting because there is something wrong with the underlying base system, which might be hardware (FW bus) related. I think.
Some things I have tried:
Resetting the SMC
Resetting the PRAM
Reparing permissions
Booting into Safe Mode (doesn't work)
Booting into Verbose Mode to observe what happens (I get the "Can't load the Bootcache.playlist" error, which I suspect is related to the screwed up FW bus)
Trying to boot using Internet Recovery (doesn't work)
Booting into Single User Mode and attempting the "fsck -y" etc. sequence to try and repair the ACL that way
So I am stuck.
I guess the question is, should I get an external HD enclosure and install Mountain Lion onto the hard drive that way and hope it works when I put it back into the Mini?
Any other ideas? I have spent a couple days ******* around with this is am running out of ideas...
Any advice would be appreciated!

Answer 1

Addendum: I read on a post here (http://forums.macrumors.com/showthread.php?t=420169) about removing some kext files in order to trick OSX into thinking that there were no FireWire ports.
I followed the instructions and removed from /System/Library/Extensions/ the following files:
IOFireWireSerialBusProtocolTransport.kext
IOFireWireAVC.kext
IOFireWireFamily.kext
IOFireWireIP.kext
IOFireWireSBP2.kext
I restarted and BAM...Snow Leopard booted crazy fast and the mouse and keyboard worked instantly.
The System Profiler says "No FireWire ports were found."
So this tells me that the FW port is probably the culprit and is messing up the installation.
So how do I hack the Mountain Lion installer and tell it to ignore the FW port, which is obviously quite dead? Or is there something I can do to the Base system that is similar?