My Line 6 Floor Pod won't turn on for me. Since it is now out of warranty I'm hoping I can repair it, but I am lost as to where to start.

The unit will not turn on. All I have done is tried different outlets, and opened it up to inspect the components. I see no warped PCB, bulging caps, or burn marks.

One thing I would like to do before I go crazy on the unit is see if the power supply is even putting out any power. I can't come up with a way using my multimeter to even test that. Any suggestions?
From what I can see, it has a standard power input jack, so you read the back of the PSU, see what the output voltage is, and whether the inside of the outside of the plug is +ve. Then you set the multimeter to the correct volatge range, and attach the probes observing the polarity above.