If you have voltage, then the power supply is probably OK. Different models use different voltages, as my two 'bots do. If both motors quit at the same time, then it is probably the cord. I have had to shorten the cord on both of them, it faults at the first attachment point on the 'bot end. The pulling and twisting of the cord will eventually cause it to either break or short internally. If it shorts, then the fuse on the power supply will open, yours sounds like a break.
Check the end of the cord, the connections that go to the motors. You should have the same voltage that you measured at the power supply. If it doesn't, then it's the cord, try to see if you can get it to work by moving the cord around right were it twists the most, as that is where it is most likely to fail. If you find the fault, then you will need to cut it, remove the short end and then re-attach it.
If it has green corrosion inside the watertight sealing of the motor connector, you've found the problem! Cutting all of the factory applied zip-ties and waterproofing materials is not fun, and trying to get it all sealed back up when you're done can be messy, but it a relatively cheap fix. I've used crimp on connectors to splice, covered with lots of RTV siicone pumped into a piece of heat shrink tubing.
Good Luck