Low Voltage Landscape Questions

I'm ashamed to admit this, but it's true. OK, so I had a low voltage set-up in place that worked fine, but the problem was that I was moving some of the lights around in preparation for running some more low voltage wire/cable to a berm I just put in. I was thinking of running more wire off the end of one of the existing runs, but I never even made it that far. I was moving the existing lights around a bit, used a utility knife to take a bit of the wire casing off so the light could make good contact, my timer went off, lights on, then sparks, smoke, etc., from the wire I was working on at the time. The lights went dim (but still on), I rushed over and unplugged the transformer. I couldn't tell if it was a fried transformer or another issue. I checked the outlet and there is power to it. I took the transformer and connected a single light to it, and nothing. I bought a new transformer and plugged it into the existing wire, and the lights don't work. I ran a piece of the wire (cut from end) to a single light, and that didn't work either. I guess my questions are:

1. Is it possible that I would need to replace all the cable (the cable went bad due to my mishap)?

2. Is there a way to test the transformer - or should I assume it's done dealin'?

Thanks in advance for any tips/help/advice.