Same thing happened to me after I replaced my Turn relay after putting in LED lights, I just happened to get the battery beyond its last chargeable parts. The only thing that would come on was the head lamp, very very dimly. We hooked it to a volt meter (the battery), and it was barely putting out 3 volts. While I still think there's a chance it could be the starter relay, take the battery out and take it to autozone/advance. They'll check to see if it will accept a charge and/or if it's really dying. My bike is a 2002, I bought it about a month and a half ago; it ran through the dealership's shop fine, but they didn't test the battery to see the output. New battery fixed it; fired up with no problem.
Try to push start it, if it cranks over, your electrical system is 99.9% sure to be good. If not, you've got the starter relay and battery to check (my money is still on the battery!)
Best of luck man, report back and let us know what you find!
2002 Honda Shadow 750 Spirit
TMC Cateye LED Taillight
Harrison Specialties 24 LED Turn Signals
Cobra Highway Bar
Custom Chrome H/B Pegs
DTI Mirrors (Standard adapted for Metric)