I've got over $4,500 US invested in DJI drones. I've crashed them so many times that adding up the repairs probably adds another Hamilton or maybe even two, to the mix LOL. Most of the crashes were inside my house... i don't fly indoors anymore.
Every crash I made was pilot error. However, once I learned how the system worked, my crashes ended. I learned how to adjust my battery warning settings; of which, there are two. One is the initial battery low warning, and the second, its "I hope your were paying attention because i'm going to land' mode. Both of these are operator adjustable.
I played around with both and ending up with the first at 50% (but don't care for the beeping). I like to know where the half way point is. But the variables such as wind direction, battery temperature, ambient temperature, altitude, obstacles, ground speed, etc all have to be factored in during your flight.
I drive a chevy Volt. In 70 degree weather is says I get 47 miles on a charge. When the temp drops into the teens, I get 27 miles on a charge. The numbers are based on me driving on a flat plain with no wind (just the drag created by forward motion, which increases exponentially as speed increases).
The same holds true for a drone. Just because the battery indicates a full charge doesn't mean anything other than it has reached full capacity. What you do with that charge is crucial to a successful takeoff, flight, and landing. DJI only provided us with the components, its up to us to educate ourselves on the system.
YouTube has a video of someone reaching 15,000 feet in a drone then complaining that it crashed due to depleted battery. First off, 15,000 feet is putting peoples lives in danger in the air. Turning it into a vomit comet by depleting the battery to zero at high altitude is putting peoples lives on the ground in danger. Do some calculations using Newtons law and Imagine getting hit is the head by a battery descending from just 100 feet.
If I were so inconsiderate about crashing through the windshield of aircraft at 15,000 feet ( some of which are traveling at 8 miles per second), that I couldn't resist the temptation, then my DJI Mavic has the ability to allow me to shut down the motors at any point, free fall to a desired altitude, and restart for a safe landing. Would I ever try it, absolutely not. I.m a pilot as well and the thought of hitting a drone at even 1000 feet is a horrifying thought.
While my initial post may have seemed harsh, it simply because its people like you who break the law,and who don't know what they are doing with respect to aerospace and aircraft, put peoples lives in danger. Then when things go wrong. you look for someone to blame.
Summary:
You flew your drone above the legal altitude, thus depleting your battery in the process. (keep in mind that temperature drops anywhere from 1 to 5 degrees per 1000 feet, depending on the weather and geographical region)...remember the chevy volt, less distance in the cold, less distance climbing mountains)
You set your auto landing at 20%. Nothing wrong with that but don.t complain when it does exactly what its designed to do. ( i flew with the wind once to 50% battery. When I turned towards home, to my surprise, my ground speed was almost zero. my first instinct was to locate a field and prepare for emergency landing, which I accomplished, Afterwards, I simply got in my car and followed the blue dot on my Go 4 app towards the red plane icon, and bingo, it was right where i expected it to be). I did rush though, just in case a hound dog happen by, a drone would make for a great chew toy.
If you weren't able to find your drone then I suspect anything from the battery being dislodged upon impact, thus no GPS signal, to the drone sinking to the bottom of a pond. Or better yet, a blast from a shotgun as it hurled towards some unsuspecting hunter.
I actually hope you find your drone, take some of these posts, and put the criticism to use. I don't need you to like me or dislike me, just be safe, and for Pete's sake, stop blaming others.