Well it only takes 10 seconds to test the power supply with a meter or small light bulb to see if it is putting out power’ if not its the power supply. You have to be pretty dumb to buy a whole Power cab before just testing the wall wart.
Problem is, you need to put at least about half the rated load on the power supply to know if it really is good or not, just connecting a meter might read proper voltage but a meter by design is high impedence - doesn’t draw much power to avoid influencing the device under test. A fairly common failure in a power supply is where it just falls on its face under load. So an unloaded test will make you think it is just fine.
FIRST step for a DCC system should be a reset of the system, when odd things are happening. If that doesn’t help, check the power supply. The system is, after all, a small computer. Rebooting often fixes weird issues.
–Randy
How in the heck do you reset a power cab if it will not came on. No if their is no current coming out of the wall wart its bad.