To get to the screws beneath the keyboard you need to take some keys off. You can use either an opening tool or an opening pick. The first picture shows how it should look like with all the necessary keys off (12 in total).
The four longer keys from the fingerboard are to be handled from the left side to get them off.
The eight smaller keys need to be levered from the bottom up.
Unlock the flex cables by pushing the two black nibs on both sides of each connector.
Now you can pull the flex cables out and remove the keyboard completely.
When installing the new keyboard, make sure to remove the protective film underneath the screen.
The OP-1 has a mode to test specific functions. You can enter it by holding the "COM" button while powering on, then choose the function test (2). You don't have to complete every test and can power off after the keyboard test.
Now the UI board is free to take out. You can grab it by the knobs and start lifting it on the right side half way out.
On the left side the speaker and its cable might be in the way to get it out straight. Just move it diagonally to the right to get it out completely.
Make sure the black plastic mat underneath the UI board stays inside.
After reassembling you want to check the board with the internal test function. You can enter it by holding the "COM" button while powering on, then choose the function test (0).
No need to replace the adhesive tape as long as you leave it attached to the op1 or to the back of the display itself. So when you go to put everything back together, slot the display back into place, the adhesive tape that is there should stick very gently and when you go to put the keyboard with the display glass back, everything will be held in place.
Also, this guide skips over detaching the ribbon cables when you are removing the keyboard, the two connectors each have two (2 on each port) very small black colored locking mechanisms on the left and right of the cable's port, using a spudger you can push those locking mechanisms up about 2mm, and the ribbons should detach from the ui board seamlessly allowing you to gently pull them out. When putting it back together, insert the ribbon cable evenly to the new port, and push the locking mechanisms into place (reverse from what you did before).