Mac mini does not boot into any mac os
I have a mac mini mid 2010 which absolutely refuses to boot into mac os. About 2 years ago I decided to clean the mac mini, so I proceeded to open it, reapply the thermal paste and cleaned the cooling fins and upgraded from a 1gb stick to 4gb, after which the mac would just get stuck on the loading screen. When it used to work it took about 3-4 minutes to boot, but after the cleaning it would load to the end of the bar and just get stuck there. I tried to boot into recovery mode which it did not go into, tried internet recovery which just kept loading and loading and would not go past that. I then put the old ram stick back, reset the nvram, pram and the smc but.. that did not resolve anything. I also removed the cmos battery and replaced it for a new one which didnt do anything.
I got frustrated and installed a fresh hard disk and tried to boot the mac into a bootable mac OS X usb which I made using transmac on windows as I do not have access to any other mac. When I tried to boot into the usb, it would again load to the end and just get stuck there and would not go past it. At that point I gave up and left it for 2 years. I tried to fix it again this year and I tried various other things like creating a bootable usb from a mac os virtual machine which did not work. I got fed up and tried to install a different OS, like windows which would not work. The only OS I got to work on my mac mini was Ubuntu. I have no idea what I can do anymore.
Is this the only apple product which refuses to boot into Mac OS? I would really appreciate any help I can get because honestly.. I am in a limbo with this machine.