Black Screen after Windows Logo with responsive mouse

Here is the full story (feel free to skip if you don't think it's necessary):

So my dad and I found a $5 computer at a garage sale that had a 1TB HDD and a better processor than our current one in our family computer so we decided to get it and move our HDD to its motherboard and I install the 1TB HDD into my computer. So after we put the "new" computer together with pieces of our "old" one, I make a USB version of a windows 7 repair disk so that the OS will be able to update itself to the new hardware. But for whatever reason this doesn't work and the OS doesn't want to boot, it would keep freezing during the startup animation for the Windows Logo. Anyways we mess around with it for a bit and decide we might as well just put our old computer back together. So we do so and put all the parts in correctly etc. etc.

So this is where the problem starts. Now when we try to boot up the computer, we see the full "Starting Windows" animation however it remains up there for WAY longer than usual (at least a few minutes) eventually it goes away and we are greeted with a black screen with a movable mouse and nothing else. We tried waiting a few hours but that changes nothing. I then tried booting into safe mode but I still couldn't get in. I then went to the "Repair" section by pressing F8 before the computer booted and ran the first option (I forget what it was called but it was something along the lines of a "startup-analyzer" that would find and remove and problems that happened during startup) however that reported that there were no problems during startup and that everything was perfectly fine. I then tried to restore from an earlier point however that just gave me the message that the restoration failed. I then ran the memory diagnostics check and it showed that the ram was perfectly fine. So then I opened up the terminal and found and went to the correct partition and ran chkdsk with the options /f/r. That took a few hours however it claimed that there were 0 bytes of data in corrupted sections and that everything was fine.

So now I'm left with a confusing problem. Everything looks "ok" with the hardware (as far as I'm aware) and we attempted to not damage anything during the process of switching different computers, so why isn't the operating system starting? Does anyone have any ideas or fixes?