Chosen Solution

What happened:

  1. I changed thermal paste, no issues
  2. Loaded the game with fans on max (used utility), got good stats
  3. Changed fans speed to system control
  4. Game freezed, Mac went into the bootloop
  5. Shortly after it stopped, only fans were silently spinning
  6. I checked all of the basic suggestions such as reset this and that, but black screen is still there with fans silentry spinning I recorded entire process on video, here’s the link if this might help you to help me: Macbook 15" 2014 Thermal Paste Replacement

Disconnect the battery, then press the power button for 15 Sec’s to clear SMC. Now plug in the battery and restart your system but this time press the Shift (⇧) key to enter into Safe Mode which by passes the discreet GPU your system has. Did it boot up? Reference: Mac startup key combinations