The Inspire 2 likely drifted because it lost GPS indoors and switched to Atti Mode, where it can’t hold position and will drift with air movement. The metal environment likely interfered with the compass or IMU. VPS might not have worked due to poor lighting or floor texture. For indoor flights...
It would likely take about 30-45 minutes, needing 2-3 batteries. Divide the roof into labeled sections for easy reference in the footage. Charging around $300-$600 is typical. Consider adding high-res photos or thermal imaging for better results.