Hi Andre,
The thing about your phone is that there are two ways to replace the screen; with or without the frame. With the frame, the LCD comes preattached to the midframe of the phone, which means you have to completely disassemble your phone and transfer all of the components to the new screen+frame assembly.
The other way to do it is to just replace the LCD. In that case you have to carefully remove the LCD from the frame, then replace it with a new LCD. Virtually all of the written step-by-step iFixit-style guides only show how to do the full frame replacement and not the LCD only replacement. Here's an example.
Manuales / OnePlus 7 / Fullscreen
However, I did run across a YouTube video showing the LCD only replacement, which is basically what you need to do.
Oneplus 7 LCD Screen Replacement - YouTube
The video recommends using either a precut adhesive sheet or something called B7000 adhesive. I've never used the liquid style adhesives on my many phone repairs; I'm much more comfortable with the precut adhesives. Note that in order to do the job right, you'll have to open up the rear of the phone so you can unplug the LCD in order to place the adhesive correctly on the frame. Here's an example of what I would use.
Replacement for OnePlus 7 Front Frame Adhesive Sticker
It might be possible to put the replacement on without cutting the actual adhesive if you cut out the center backing to where the screen can be fitted through the middle so it can be laid down on the frame with the screen still attached, if you didn't want to go to the trouble of disconnecting the LCD.
If you do decide to unplug the LCD, which I would suggest as the better way to do it, you'll also need the rear cover adhesive sheet as well. A suggestion I might make is that those adhesives are cheap enough that I usually buy a couple when I order them. The thing is, they're all too easy to mess up; if you don't get them on just right the first time, it's almost impossible to get them off in order to reposition them. So you end up with a tangled mess of adhesive and have to wait until you can reorder before you can put your phone back together.
Hopefully that'll get you going. Good luck with it; let us know how it goes!
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It sounds like a problem with adhesive. I would recommend using new liquid adhesive (after scraping any existing adhesive off). However, I don't have a recommendation for the liquid adhesive you should buy. Perhaps someone else on the forum with more experience using liquid adhesive can elaborate?
crwdns2934271:0crwdnd2934271:0 Andrew S crwdne2934271:0
@andrewsawesome Thanks for your input. I'm not sure how adhesive are supposed to work, but now I'm not sure if that's the issue because the back of the screen is very clean/smooth. Wouldn't an adhesive leave some kind of marks on the surface?
EDIT: Oh nevermind it's definitely the adhesive that's gone. Now iFixIt offers back cover replacements with an adhesive. Do you think the adhesive for the back cover can be used for the screen?
crwdns2934271:0crwdnd2934271:0 Andre crwdne2934271:0
@andre89815 If you're referring to the precut adhesives, then no, you can't use the rear cover adhesive on the front. I've posted a link to the front adhesive you could use in my answer.
crwdns2934271:0crwdnd2934271:0 Jerry Wheeler crwdne2934271:0
All of a sudden the display has gone since last one month. Where to get it repaired.
crwdns2934271:0crwdnd2934271:0 Sameer Marathe crwdne2934271:0
All of a sudden the display has gone since last one month. Where to get it repaired. How much will it cost?
crwdns2934271:0crwdnd2934271:0 Sameer Marathe crwdne2934271:0