Would recon this being a warranty thing. I will contact NOKIA support today but most probably leave it in a service center for replacement.
Since we are at least two with the same problem at a short time this bound to be a HW problem.

Note that if you lean the screen to look from above or from under you may see a faint NOKIA logo initially that makes up those grey lines. Then you will see that it´s infact booting but with corrupt screen.