How can I force Sync system reboot?

I have the Sync system info tainment module. After replacing a bad battery the system works intermittently. The SUV gets used spairingly so sometimes the battery dies between uses. When we jump the battery, sometimes Sync comes up, and sometimes it doesn't. Any thoughts on how to force a reboot? Is there a hidden key combo to force a reset? I've tried pulling fuses, doesn't always work surprisingly...