Black screen, with vertical white and grey stripes, happens quite often!
Have you tried disassembling the display, cleaning the contacts and reassembling it?
Another possibility to check if the display is faulty/broken, would be, to exchange your display with someone elses. Do you happen to know someone with a FP2? If not, there are lots of #fairphoneangels, that can help in such cases. Maybe one is living in your vicinity.
Otherwise you could try and post an area for contact in this forum and some other user living in your area might be willing to help you.
Finally you can and should contact support, if nothing else helps.
Thank you, Bert, for the replay!
With what do I clean the contacts?
Alcohol will do.
Best medical alcohol (as that dries really fast) and a Q-tip.
From the iFixIT page on what to do with water damage
Ideally use a 90% or higher concentration available from a pharmacist or drug store. You can use distilled or deionized water as an alternative cleaning fluid, although this will take longer to dry. Avoid solvents such as ketone, acetone, or naphtha.
(Though that’s not exactly about cleaning the contacts only.)