Bernie, I have never been inside the PSR-S910, but I have been inside the PSR-2000, 3000, 5700, and many others. I can assure you that at the very least, it will be quite difficult. Now, do you need to replace the entire case, both top and bottom? If so, I would not do it. There are dozens of small boards, all anchored to places you can not easily access. And you need to be able to carefully unplug tiny little plugs without damaging the hair thin pins, then put them back in place again during reassembly. It would take a good technician hours to perform this task.
If you have any photos of the damage, please post them so we may be able to come up with another remedy. I once repaired a friends keyboard that smashed the end in while carelessly walking through a door and jammed it into the door frame. I was able to epoxy the small pieces back together, then filled in the open areas with body putty, sanded it down, and repainted the damaged area. When it was completed, you could not tell it was damaged from the outside.
Good luck,
Gary