Single line on screen

Hi Ranjan,

Generally any line on the screen indicates damage to the OLED itself and is not repairable. If you would post a picture of what you're seeing it may help us make a better diagnosis, but I strongly suspect you're going to either have to live with it or replace the entire screen.

I wasn't able to locate any iFixit-style step by step instruction guide for your phone, but there is a well done YouTube video that I'd suggest using if you want to repair your screen by yourself.

OnePlus 8 Pro Screen Replacement - YouTube

Unfortunately for you, your phone is still relatively new and uses a curved screen OLED display, which means the part is still fairly expensive. In general I saw prices that averaged over $200 USD, but there were some exceptions. Here's the cheapest one I came across on my rather cursory search; a more extensive review of sites like Amazon, eBay and AliExpress and others may turn up something more cost effective for you.

Replacement For OnePlus 8 Pro One Plus 8Pro 1+8 Pro IN2023 IN2020 IN2021 AMOLED LCD Display Touch Screen Assembly Original – iProGadgets

If you decide to take on this repair yourself, be sure to take lots of photos as you work and you can use those to create your own guide to that repair for those who follow behind you and need to do the same fix. Your efforts will be very much appreciated by the community.

Create a new Guide - iFixit