My AC unit won't blow cold
Sounds suspiciously like your A/C lacks a suitable time-delay relay to prevent rapid on/off cycling, which is generally a bad thing (and why those are usually included.) 

In short, when you "flipped off" the A/C circuit breaker, you should have waited 3-5 minutes before flipping it on again (or the system should have waited that long before attempting to restart the compressor.) The fan motor capacitor (or starting switch) failure might simply be coincidental to the actual failure, which could be compressor damage. At about this point I'm riding the hairy edge of my knowledge (I know that turning the compressor off and back on in a short time is bad, I'm vague on the exact mode of failure this is likely to cause, though I think it may have something to do with the refrigerant vapor condensing to liquid that is incompressible...)