Car had complete electrical power loss. No lights or sign of life. What could be

Have you tried jumping it yet? Could be just a dead battery. Maybe the alternator is on its way out and took the battery with it. Try and jump it, drive it around a bit. You may want to call a shop and have them diagnose the issue before buying parts. http://repairpal.com/bmw-within-10-miles-of-spokane-washington-99224