I bet the compressor locked up, there's possibly a burnt wire, or one of the starting components took a dump(relay, or capacitor) , especially if the unit doesn't work on any outlet. You Might have had a dead short, meaning that the hot leg and neutral were touching somewhere in the box, ,maybe because the insulation was no good, and now the insulation is melted so the power goes no where, which is why nothing happens when you turn it on. Could also be a bad thermostat. Compressors don't get dirty, condensers do. That's the coil on the outside of the box that rejects heat from the box.
Take it back, or find a friend that knows how to use a volt/ohm meter and troubleshoot the thing.
Don't mess with electricity, if you don't know what your doing, it's more dangerous than any MA horde.
Good luck man, warm beer sucks.

The thermal overload is a little disk looking think, with two wires going into it, usually under the cap on the compressor. With the unit off, and unplugged, you can check for continuity.