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.