I just replaced my heater core & blower motor. I am having electrical issues.

All fuses good?

You might need a good diagnostic technician to check this out for you, and his/her approach will be to "forget" that the heater core was just done, pick one of circuits that isn't working correctly and troubleshoot it like any other failure. By doing this the technician will go straight at the problem no matter where it is at. Once that one failure is corrected, then step back and see if that was a common issue to the other systems that aren't working.