Removing the main board in the Rising is fairly easy although it will take some patience. After you have the case opened, remove all the rotary knobs from the top of the backside case. Then remove the screws marked in the following pictures:
Start removing the board from the side opposite the power transformer. Once you have it almost all the way out, the one tricky part is where the line-in sockets and such are. That portion of the boombox is tethered to the main board by rather short wires and if you are not careful, the wires will most likely break at the solder joint. It happened to me and I had to resolder.
That's pretty much it. You'll be able to get to all the switches from there. Just be careful and be patient.