White screen at boot, Wiped Drive and reinstalled os, Zapped PRAM several times

Then your laptop has a bad GPU so you will only be able to use the laptop with the Intel GPU. Keep in mind the GPU failure could get worse to the point where the laptop may not even boot or power on.

As far as other apps to use besides TechTool Pro (TTP), what features of TTP do you use? I have not used TTP in many many years and only tried the app again a few years ago and found it severely lacking (even back in the day I was never really impressed by TTP).

Here is an article that may help.

• If your Mac starts up to a blank screen - Apple Support

Have you tried running the Apple Diagnostics to see if any hardware issues are detected?

You don't provide the exact model of your Mac or the OS used on it. You can get the exact model by entering your serial number here:

https://checkcoverage.apple.com/

I don't know what OS or drivers the TechTool uses to boot which greatly affects the diagnosis as you may have more than one problem with this laptop. It does not surprise me that a hard drive is worn out or failing, but a hard drive doesn't usually just cause a white screen during boot. If you have a 15" or 17" model (you posted in the MBPro forum), then most likely the white screen issue is being caused by a bad GPU. You can try forcing a 15" or 17" laptop to use the Intel GPU instead by booting into Safe Mode in order to install gfxCardStatus:

https://github.com/steveschow/gfxCardStatus/releases/tag/v2.4.4i

https://codyschrank.github.io/gSwitch/

Or if Safe Mode does not work you may need to resort to these instructions to force the laptop to use the Intel GPU:

http://dosdude1.com/gpudisable/

It would have helped to know the exact errors reported by TechTool. By the way TechTool is not a great app and really is not needed on a Mac. Certain features provided by TechTool are better done by other individual third party apps, but most of the features of TechTool really are not needed at all.