Ok so I DID IT. Finally managed to replace the LCD and everything went as expected. Huge relief phew. This screen was sitting in the box for a couple months but I didn't dare to open the monitor lol. Turned out its a lot simpler than I was thinking. Some tips below if anyone wants to replace the monitor.
1 - First thing first, you need to establish whether the LCD is bad or the main board or power board have bad caps. A completely dead monitor that doesn't turn on is a good indicator that power board is busted. Likewise a flashing screen with stripes across display etc indicate problem with board. My LCD started showing signs of pixelation with every other lines of pixel, like interlaced and resolution cut in half. My instinct told me its a bad LCD.
2 - If its the LCD then look up your monitor LCD panel manufacturer and specs. A good starting point are:
https://www.displayspecifications.com
https://www.panelook.com
You can also open up the monitor and the LCD panel model will be on the panel sticker. You can find plenty of suppliers on ebay and Aliexpress by putting panel model #. Pay attention to reliability of seller and terms and conditions in case if you get a bad display. Don't go for the cheapest just for being cheapest.
3 - Don't rush things. Take your time and be gentle and careful not to break or cut any wires.
4 - If you're a complete newbie in this like myself, then prepare a plan and checklist so you don't mess something up. Have all the tools ready, a blanket, and you need plastic tools to open the monitor shell clips, like the ones provided in iPhone battery replacement kits. Also I recommend putting your phone in video recording while disassembling the monitor so you can always go back and check where things came from.
5 - During disassembly, its a good idea to use a label tape or paper tape to stick and put notes on which cable came from which connected. Also you can put them in same orientation so you don't insert things wrong way; likewise, what bolts and screws came from where. You can group them and label them. Mine was way too simple, just two sets of screws and LCD would be detached.
6 - EXTREMELY IMPORTANT - DON'T SCREW UP THE RIBBON CABLE. Seriously this cable is hard to find, and there are so many variations, pin configurations and specs that you'll have a tough time finding the right one, and chance of getting wrong cable is high. Again check in display specifications as to what type of cable is used. There are two main types, an LVDS, and the newer eDP (embedded displayport). But they come in various pins and transfer rates. PG27VQ for example has 51 pins and 2 channel 8 bit transfer. Even more confusing is a lot of sellers don't label the cable right, some just call all LVDS and some don't put any further specs. Long story short BE CAREFUL NOT TO DAMAGE RIBBONS. This also goes for other smaller ribbon cables. Your only chance of buying is from Aliexpress and it takes a long wait time.
7 - You can search for monitor disassembly guide or service manual, but chance of finding your specific model is slim to none. So better look for a model that is closest to yours as most same line models open similarly. I found Youtube video of PG27UQ disassembly which looks closest to the shell of my monitor. Put your plastic tool to pry open the shell, work your way around. Don't just pull the cover out coz there is a connector, your model may differ but you may have display control board cable or rgb cables.
8 - It's a good idea to just disconnect the cables from current LCD and connect it unassembled to new LCD to test if new LCD is working or the problem really is LCD. This way you don't have to go through whole panel assembly only to find out you got a bad screen from seller.
9 - Rest is pretty easy. Once you have removed old panel and put new one, close the shell only slightly. Connect cables and test everything, then completely assemble everything back together.
10 - First time you power the monitor it might do some kind of calibration and keep flashing or going on and off etc. Be patient and its normal. Also my PC was detecting the screen but no image is being output. I had to disconnect and reconnect displayport and then image came. So these things do happen, not a sign of bad display but first time set up.
11 - I recommend resetting monitor settings menu and redo all settings. Mine automatically enabled 165Hz overclock. I had it turned off. Also check NVIDIA control panel, your display may start at 60hz while it was set up 120 hz before, just change things back and make sure to test a few 3D games.
12 - Run dead pixel tests etc. Mine I got lukcy, no dead or stuck pixels. All good so literally a brand new PG27VQ (with exception of boards lol)
That's all.