I tried and - no. Grey screen with crossed circle. The Ivy Bridge drivers are not included in the standart 10.7.4 updates, you can wait for 10.7.5 or you'll have to reinstall.

I am using 1.5V RAM in the MBP 2012 13''. No problems. Corsair Venegance CL9 PC3-12800 2x4GB

Did you hold alt when booting while the dvd was inserted? Just boot while holding alt, it will show you the option to boot from the Install DVD. Then, you can check you Hard Drive (Disk Utility) or perform a Hardware Test.

I'd recommend upgrading to 4GB (if your machine supports 4GB), Mountain Lion with 2GB won't be a joy to work with. If your MacBook doesn't support 4GB it likely not support OS X Mountain Lion, as Apple restricts the new OS to true 64bit processors.

Try booting in safe mode (holding down shift while starting the mac). If that works you can troubleshoot. If that doesn't help you'll need a disc to reinstall OS X.

Yes, you can upgrade to 16GB of memory. Apple doesn't support it officially, but third-party websites have checked it.

The replacement program is still up and running.

Hey! Try removing all the RAM, wait for at least 5 minutes, and then reassemble. If that doesn't work, try this.

No, the Macbook Logic board won't fit in the MacBook Pro. Maybe you forgot to plug in the battery connector? Happened to me once :) You should also check if the bottom plate is installed correctly (and tight), there are these nasty golden button on the logic board that check if the computer is assembled.

I don't think this is hardware related. Otherwise, Safe Mode wouldn't help. Start normally. Check Console.app for extensive error reports. (Look out for kernel error messages, maybe you'll find the bad kext and are able to disable it, see later in the answer.) Otherwise: Start in Safe Mode. Disable any Login Items (in System Preferences / Accounts) Run the following in Terminal: kextstat | grep -v com.apple This should show you all third party Kernel extensions. You can then disable everything that sounds suspicious by navigating the Finder to /System/Library/Extensions And rename the kexts you investigated to f.ex. ***.kextbackup, then reboot (normally). If the system works, you can re-enable the kexts and login items one by one and find the bad one.