My dell inspiron will not power up. Was working on an electrical outlet and turned off the breaker. The dell was running but the barrery is dead and the laptop shut down during the course of my repair. I did not unplug the laptop prior to resetting the breaker since it was powered off. is it possible that I fried the motherboard?

Usually the power supplies protect the motherboard from an overload of electrical current. But that all depends on the amount of current. If you are going to try to troubleshoot/repair this, gain access to the power supply and check to see if the power supply outputs are working using a power meter.