Display on Macbook Pro AND Macbook Air get vertical and horizontal lines at the same time

My gf was using her Macbook Pro (its either a 2013 or 2014) this evening when her monitor randomly became discolored and blurry, then displayed VERTICLE lines across the screen. This laptop also has a brand new logic board, recently replaced by AppleCare.

She immediately tried restarting the device using:

Diagnostic command ("D" and D+option" key(s) at restart)

PRAM command ("command+option+p+r" keys at restart)

Safety Mode command (Holding down the "shift" key at restart)

Startup Manager (Holding down the "option" key at restart)

Recovery Mode Command ("command+r" keys at restart)

Network Boot Command (holding down "n" key at restart)

Verbose Mode Command ("v" key at restart)

Single User Command ("command+s" keys at restart)

Every time the result was same: the screen briefly flashing once and then going black with VERTICAL white lines.

She quickly grabbed her 2015 Macbook Air and turned it on to continue working, but within the span of about 30 seconds the screen became blurry and displayed HORIZONTAL lines across the screen.

We both tried every troubleshooting boot key command we could think of to no avail. No matter what we do the Mac boots to a faded grey screen with black horizontal lines along the bottom of the display.

Has anyone experienced this before or have a suggested fix???

We're completely baffled. I can understand the graphics card potentially screwing up randomly on one device but two separate macs, almost at the same time, both running Sierra and one with a BRAND NEW LOGIC BOARD???

I've already scheduled an appointment to bring the two devices to the Genius Bar tomorrow afternoon but I'm hoping somebody out there might have a potential solution, or at least be able to better explain the issue for me so I'll know exactly what to say when I get to the store to help point them in the right direction so we can expedite the repair.

Any assistance would be welcome!!

-Chris

Thank you muchly, guys!