Newbie: Think has no power

Drove Think without issues last October (2014), parked in garage and plugged in to charge. Batteries are about 5 years old and never showed any signs of going bad.
Just tried to move it today and nothing on cluster …
Have amber solid light on charger and a flashing red light below it.
What can I check before calling local service ?
Fuses ? Where ? Battery voltage (single or total) and how to check.