If your RPI2 requires more power to drive the video

Access the boot partition and locate config.txt 

Change the following lines

# uncomment to increase signal to HDMI, if you have interference, blanking, or

# no display

#config_hdmi_boost=4

to,

# uncomment to increase signal to HDMI, if you have interference, blanking, or

# no display

config_hdmi_boost=4