Does the starter solenoid click at all? If it buzzes, it's probably the starter, the solenoid is not engaging properly. If it clicks once then nothing it's probably the battery. Even though you charged it, it may have a bad cell, may need a long trickle charge and/or replacement. Can you swap in a known good battery?
On the mechanical side, can you turn the motor over with the crank? If you can, it's probably an electrical problem.