When you compile a Cyclone® V design, the Quartus® II software generated .pin file states VCCBAT should be connected to a 1.2V power supply. This is only one of multiple supported voltages if you are using the design security feature with volatile key. Allowable voltages for VCCBAT are 1.2V ~ 3.0V from a battery power supply.
If you do not use the volatile key (either you use the non-volatile key or you do not use the design security feature), you should connect VCCBAT to a 1.5V, 2.5V or 3.0V power supply on your board. You should not leave VCCBAT floating or connect to GND because the device will not exit power-on reset (POR) if VCCBAT stays at logic LOW.
Ensure VCCBAT is connected to the correct power supply. Follow the Cyclone V Device Family Pin Connection Guidelines (PDF).