On the ultimate PO, once the back is off, you will find 4 screws holding the movement in. I had 3 screws with one missing, others report none to 1 to 2. Just another one of the numerous quality control issues with this model of the watch. But here is where I stopped and did not remove the movement. covering each screw hole was an ultra-thin piece of metal bent over it. It appears you would have to bend each one of these up 90 degrees to be able to remove the movement. I bent one and it is springy material. I chickened out and tried to bend the metal back down flush and it was impossible - again - because it was too springy. Maybe these slide out and do not need to be bent (I have no ideaa why they are there) but I was not willing to go further and reassembled. The bent biece of springy material flipped the screw off 6 times and it would have gone by-by into the carpet had I not done this in a large baggy to protect from just this kind of problem. Maybe others have the instructions on how to do this for the Ultimate PO.
Good luck.
Usil