Update drone to latest firmware first with any new drone.
For this "insufficient battery charge", try turn off everything, phone, drone then connect again.
However, I would not recommend re-calibration based on my experience. Without calibration, my drone returned home 2-4 feet off the original take off point. After calibration in open field without any large metal object around, the RTH was 6-8ft off the original take off point. That happened to two drones so I stopped calibrating for any other. That's like "if it worked, don't fix." Updating to latest firmware is a sure way to get the latest and greatest in most cases.