Why is my Mac Mini not booting?

I have been having issues with my Mac Mini 2011 (A1347) recently.

Here’s a list of the issues:

• The Mac Mini will usually not boot up all the way. The progress bar gets to about 60-70% and reboots. After about 3 times of this, the fans get loud and there is no display output (I can fix this by resetting the SMC).
• If the Mac Mini does boot (rare), it will reboot after about 10-15 minutes. I can usually get it to boot after resetting the OS or running hardware diagnostics.

Here’s what I’ve tried:

• Different surge protector
• Replaced the PRAM battery
• Replaced the drive (replaced it with an SSD)
• Reinstalled the entire OS (multiple times)
• Disabled the Dedicated GPU by following this article: https://discussions.apple.com/thread/750....

After doing some research, I’ve seen people that have had similar issues, but fixed them with one of the following:

• Applying new thermal paste. I feel like this probably isn’t the issue because I would think that the CPU/GPU wouldn’t overheat right when the computer boots up, but I could be wrong. Even if this isn’t the issue, I should probably reapply the thermal paste at some point.
• Resoldering / reflowing the graphics chip. I have discovered Radeongate, but not all of the symptoms match mine. For example, a lot of people have said that they see a green apple logo, have a distorted output, etc. but I am not experiencing any of that. As I said above, I have tried disabling the dedicated GPU, but that didn’t seem to help. I do not have much experience soldering, but it’d be worth a try if this is the issue.
• Replacing the power supply

One last note, safe mode works fine. This makes me think it may be an issue with the dedicated GPU. If so, is there a better way (than what I tried before) for me to disable the dedicated GPU to ensure that this is the issue?

Thanks for the help!