No power to starter
 

Yamaha 2007 gas golf cart dead
No starter power, no headlights, no turn signals
All fuses found are good
New battery tested good
Bypassed ignition switch with no change

What else should I check /try?

Dead electrical system
 

Follow the ground and positive wires from the battery to the next point of connection. Check the wiring points on the starter generator. A volt meter would be helpful.