OnePlus is actually offering repair out of warranty which is reasonable. If it is just the screen, then it is $206. Not many have seen this. https://www.oneplus.com/support/repair
I just replaced the touch screen on a ipad2 and the replacement one did not come with it. it seems just fine without. I do suggest replacing the wifi antenna though. It rips easy and is stuck to the glass.
Do not use water on anything that contains Lithium. Lithium will react violently with water. Look it up on YouTube to see how violent. Sand, baking soda, or CO2 fire extinguisher are way better options. Though not as violent as pure LIthium it is still violent and dangerous. https://www.youtube.com/shorts/Wq1J8n_gm...
You should pull up from the bottom of the button. It will hing up and pop off easier and less chance of breaking the button. There is a hing on the top side of the button to pivot down to the bottom where the button is. The clips are near the bottom of the button. You are more likely to break the pivot pins doing it from the top.