If all you need off is the faceplate, skip all of the screwdriver-based steps, and just remove the dirt bin(step 7) and start from step 11 at the rear.

If all you need off is the faceplate, you can start at step 11 and skip the 1-10. The bottom and bumper assemblies seem completely unrelated to the faceplate. I removed the dirt bin and started lifiting at the back edge, then worked around the faceplate and it just popped off with no damage.

There are 4 long friction tabs around the circumference, and no tabs at the center. Once the outer friction tabs are free, the center circle of the faceplate comes off cleanly, leaving the display panel, control buttons and the chrome-ish ring. Under the 'IR' in the IRobot logo on the faceplate is the SCI port, more plastic and a number of screws to get to the motherboard.