I knocked a glass over and the computer worked increasingly erratically even with an external keyboard and mouse.
I'm beginning to get good at this. Swapped a keyboard on a MacBook for my daughter. Did this one on my MacBook Pro. Will probably do another on my wife's computer. The repair was quite straightforward but be warned: Apple seems to make a lot of small changes during a production run. If an instruction doesn't seem to match the physical reality you're dealing with, the edit link for the step will take you to a discussion. Somebody has already found that your keyboard has 12 little screws and 6 tabs and not 10 screws and 4 tabs.
A muffin tin is a good place to put screws, one muffin per step. Work backwards during reassembly.