Please help me diagnose this terrible malaise  

According to the service manual for your laptop you have the following:
Dual Storage Configurations
1 TB + 256 GB PCIE SSD

Here are your drive options:
2.5 Inch = SATA Hard drive or SATA SSD
M.2 = SATA SSD or PCIe SSD

You said you bought a Samsung 500GB 860 EVO which was to replace the original SSD.
You then said the tech installed it along side the original SSD and removed the 1TB hard drive.

The only way this makes sense is you bought the wrong type of SSD.

There are two versions of the Samsung 860 EVO:

* Samsung 860 EVO 2.5 Inch SATA


* Samsung 860 EVO M.2 SATA



It looks like you bought the 2.5 Inch SATA version instead of the M.2 SATA version.
That meant the tech had to remove the 1TB hard drive to install it.

Another confusing thing is that you now have a Samsung 870 EVO M.2 SATA 1TB.

I have only seen one version of the Samsung 870 EVO:

* Samsung 870 EVO 2.5 Inch SATA


I am very familiar with this drive because I just bought bought a 1TB one a couple days ago.

I think there was a miscommunication between you and your tech on what your upgrade options were.

Jaylob4 said:

Might it not be poorly seated RAM?

Moving the laptop hinge back and forth wouldn't affect the RAM. Also the RAM is pretty tight in a laptop, compared to a desktop.

BUT. the cable from the video section to the screen, does pass through the hinge area, so would be the most likely culprit.