Make sure your steering servo is in channel 1 and ESC in 2.

Should not need an external battery box.

Need to make sure battery is charged.

Flashing green from what I can find means throttle applied. First check your trims on the radio to make sure everything is in neutral. Esc will go into safety mode if it starts up with throttle on.
http://www.hpiracing.com/assets/docu...c_glb-m-v1.pdf