Based on some of the previous posts that have entered the realm of the "blame game" I'm going to take a slightly different path with this post.
Anyone that fails to learn how the battery is supposed to be installed and secured in a Typhoon H, H Plus, or 520 that experiences a battery separation because it was not fully inserted has only themselves to blame. They were informed in the system instructions and latch information has been extensively described in this and other forums referencing the products.
The latch design functions perfectly when the battery is fully inserted, it cannot self unlock, and will usually remain locked in place even when the aircraft is crashed. Failure to adequately preflight the aircraft to assure the battery is locked in place is operator error. It's not a design deficiency as the design functions perfectly and is simple to use. Failure to understand how the battery should be installed is operator error, plain and simple and people should not try to blame a manufacturer for their personal failures. Having a battery separate in flight is operator error. There's nothing wrong with the battery latch design but there is obviously something wrong with the way many operators have addressed preflight inspections, flight safety, and their comprehension of system components for which they are totally responsible for using. The battery is supposed to separate when the latch is released so blaming an improperly installed battery for separating in flight is like blaming a compass for pointing north.
Any aircraft owner that modifies their system in any way assumes full responsibility for any later failures. If they are not qualified engineers in the fields of electrical, software, firmware, mechanical, avionics design, and RF certification they lack the ability to accurately predict the outcome of their modifications. Lacking system schematics, design specifications for the command and control system, electronic speed controls, GPS system design, and other functions any modifications they elect to make are being performed on a "best guess" basis. Unless extensive, comprehensive testing on altered systems is performed, comparing previous performance against current performance, those making modifications are at best hoping for an improvement and have nothing to provide a sound basis for initiating a modification or for assuring their modifications do not negatively impact other critical portions of the flight system.
Anyone that elects to use their system in a manner that exceeds a manufacturer's published limitations becomes a test pilot. Any issues experienced with the C2 and video links is on their back, not the manufacturer's. A manufacturer makes a clear statement when they publish range limitations and those exceeding those limitations do so of their own volition. They are choosing to exceed manufacturer limitations, nobody and nothing forces them to.
Our FAA does not have any certification standards for "consumer drones" There are no regulations referencing how they should be made, how they should work, or how they are flown. Current regulations are mostly applicable to where and when they can be flown. Our FAA DOES make commercial operators responsible to assure drones are safe for flight so if anything happens during a flight that causes a crash or incident the responsibility for that failure falls on the operator. From that point forward the operator will be responsible for post crash/incident analysis to determine if the event was operator or system failure. Not the owner as the owner and the operator can be different people. It falls on the operator.
To my knowledge, no manufacturer of consumer drones has presented any part of their systems to the ASME for certification testing. Making that a little worse is all of them make it a point to limit what can be reviewed in their flight controller coding. No consumer drone manufacturer provides any level of flight test data that would enable a review of their test practices. That means that no consumer drone manufacturer has made any attempts to obtain FAA certification. As the FAA has yet to develop certification standards (that will soon change as aerospace drone manufacturers have been submitting designs for certification) consumer drone manufacturers are still free to use any components and manufacturing processes they want to with absolutely no assurance to the consumer they will function as advertised or assuring the life cycle in which their systems should remain safe and reliable. We need to get it through our thick skulls there is nothing in place establishing measurable, repeatable QA standards.
It should be mentioned that since 2013 many hundreds of one brand of consumer drones experienced fly away's, power failures, loss of control, GPS /compass failures, camera/gimbal issues, and flight controller failures. A great many of those that experienced these failures never obtained any satisfaction from the maker, yet people continued to buy them in enough numbers to give that brand over 70% of the market share. Yuneec has experienced similar issues but either due to lack of sales volume or because of better QA methods, not anywhere close to the quantity the other maker has. It should be noted that Yuneec established and maintained a much better record of replacing lost models than the other brand over their entire period of drone manufacturing. EVERY consumer drone manufacturer has had and will continue to have their share of system failures and this condition cannot and will not change until design and certification standards are imposed on the industry. If you think drone are expensive now the current costs do not begin to approach what they will be once certification becomes mandatory. That cost will increase tenfold or more.
For now, regardless of brand or model, the best we can do is to become as knowledgeable as possible about the products we buy BEFORE we put them into the air. Understand how they work, how they should be assembled and operated, and KNOW how a battery is designed to be installed and maintained before we use them to minimize operator/maintenance errors that are certain to cause a crash. Develop and use a pre and post flight inspection process. If a pre or post flight inspection is interrupted for any reason, start over and run it start to finish before take off or putting the aircraft away for the day. If you don't have time to perform a preflight and post take off inspection you and your system are not safe for or ready to fly. Use a post take off performance check list to assure all flight functions are correct before proceeding with the rest of the flight. Checklists have been part of aviation for a couple generations to help prevent accidents. There's no reason we should not be using them too.