Screen tearing, stripes, flicker, distorted proportions

Hey, I get all the symptoms listed in the title shortly after I open the lid. On an external display everything is fine.

I took the machine to a free check at a certified repair shop and they told I need an 627€ maintenance, where they'd change the display. Otherwise everything seems fine. Most strikingly the laptop is perfect for 5-10 seconds when opening the lid after a pause in use.

Im trying to evaluate my options:

1. Is the display really faulty (since it works for a short while) and could I fix simply by reconnecting the wires

2. Is the display the only faulty part and I could simply fix it with a new unit for 350€+posts

3. Is there something really wrong with my laptop and money spent on repairs will end up wasted

I would greatly appreciate if you can explain what might be causing these symptoms and what could be the most cost effective way to proceed.

http://i.imgur.com/toxSFmi.jpg

Here's an image to clarify the problem with my screen, and again on external display everything is fine. Thank you in advance for helpful messages