Looks like it is some out there with power-problems on their POD XT. Same problem for me, have had this as peiodic problems for a while now.
1. I remove 4 screws in the back panel
2. Split the panel
3. Check the power-switch if it is ok or not (and it was not) by do a shortcut of the 2 terminals of the switch back (and then test it,,,,, yes,,, the XT light up), so then I know the erros causes of the power-switch.
4. I remove the power-switch in the most simple way by cut the 2 terminals in the back of the switch.
5. I open the switch with the help of a flathead scewdriver. You expand the slot of the switch and then remove the switch-head (0 1). Careful,,,, there is 1 small ball, 1 spring, 1 pice of flat metal who can fall out of the slot.
6. Remove the flat metal-plate, clean/polich/sand the contact point on the plate and the 2 piont in the switch. The reason for this is to remove the oxide-plaque who is cover the contact-points. This is a very common problem for a lot of different electronic/electric devices. This is one of the main reasons some devices contains small amounts of gold,,,, gold is a precious metall who have high corrosion resistance. IE, You should clean every point of contact.
7. Add some small amount of grease to the one side of the ball (on the spring, then the ball would not so easy fall of), and on the slide area of the plate.
8. Replace the head of the switch.
9. Test the switch with a ohm-tester. Hopefully it is ok. If not, check if you have replace it in the right way or if it is some other erros inside it.
10. Put the switch back in the XT, get a small soldering Iron to reconect the terminals again.
11. You are right,,,,, this is not rocket science but easy forward mecanical.
If any problems, I have some photoes of the repair. Good Luck !