Hi!
I have a Phantom 4 that I bought last year. It just got out of the warranty period in May. In March there was an offer, stock liquidation, batteries, about 20% discount, at a company different from the one I bought the drone. I do not know how the batteries were stored, but when I bought it, I tested it and it was OK, it had a few loads.
One night I got the drone, with the original battery, which had about 100 recharges and the new battery. I traced some waypoints with the old battery and then I lowered it, changed the battery to the new one and lifted it up. It stayed a little in the air and then dropped.
Since I bought it, I had no problem with it.
The company that I bought said it came out of the warranty so they can not fix it.
I came to a repair man who repaired drones who was kind enough and looked more closely at it and the logs and told me how he thought it had happened:
The drone fell on the asphalt directly on the landing train, so there was no engine failure, basically all stopped simultaneously. The battery jumped out of the drones and struck a rim, but did not seem to have any imperfect signs of contact. The temperature was about 20 celsius.
His conclusion was that the battery cut off the power without announcing it.
The question is: How can I know exactly what happened to prove to those I bought the battery from?

thank you!

We are so sorry to hear the crash accident and the special situation, but I'm afraid there is nothing we can do to help you, because your drone has been out of warranty, data analysis service will not be provided after warranty expiration. Besides, damage caused by reliability or compatibility issues when using unauthenticated third-party parts will not be covered by warranty Repair Service.
Maybe you can upload the flight record here, there are many customers who know very well about data analysis.

"How can I know exactly what happened to prove to those I bought the battery from?"

You can look at the flight data to see if it gives any clues.
Go to http://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight record.
Come back and post a link to the report it provides.  

Thank you for your prompt answer,
I think I did not write well, the new battery was the DJI Phantom 4 Intelligent Flight Battery, which is still in the warranty period. I bought it from another DJI reseller, other than I bought the drone, but it is a DJI original battery, just that it was stock clearance and I do not know how much it was on stock and under what conditions.
this is the link for the flight record until the crash: https://www.phantomhelp.com/LogViewer/5ONJ2HV50ZH916GVMW4N/

thank you!

Bucksy34 Posted at 2017-7-10 02:51
Thank you for your prompt answer,
I think I did not write well, the new battery was the DJI Phantom 4 Intelligent Flight Battery, which is still in the warranty period. I bought it from another DJI reseller, other than I bought the drone, but it is a DJI original battery, just that it was stock clearance and I do not know how much it was on stock and under what conditions.
this is the link for the flight record until the crash: https://www.phantomhelp.com/LogViewer/5ONJ2HV50ZH916GVMW4N/

Sorry for the misunderstanding, the data analysis service still will not be provided because the drone has been out of warranty. Your drone will need to be charged if you send in for repair.

Bucksy34 Posted at 2017-7-10 02:51
Thank you for your prompt answer,
I think I did not write well, the new battery was the DJI Phantom 4 Intelligent Flight Battery, which is still in the warranty period. I bought it from another DJI reseller, other than I bought the drone, but it is a DJI original battery, just that it was stock clearance and I do not know how much it was on stock and under what conditions.
this is the link for the flight record until the crash: https://www.phantomhelp.com/LogViewer/5ONJ2HV50ZH916GVMW4N/

I see no evidence of a battery failure.  The aircraft was flying normally, the battery was discharging normally at normal temperature, everything was good, and then the log stops.

It may have been a battery failure, but it could also have been an aircraft failure.

If you want to prove a battery failure you will have to test the battery, maybe dismantle it, and try to find a fault, but after a crash it is going to be difficult to prove that the any problem you find wasn't caused by the crash.

I think you have to use insurance for this one.

Nigel_ Posted at 2017-7-11 00:54
I see no evidence of a battery failure.  The aircraft was flying normally, the battery was discharging normally at normal temperature, everything was good, and then the log stops.

It may have been a battery failure, but it could also have been an aircraft failure.

Thank you,
I've been looking through the logs from "black box" with DJI Assistant and didn't find anything wrong with the aircraft. In fact it is still running, motor and the mainboard are ok, booting up, but it signals there is someting wrong with the gimbal.
I'm talking with the resselers from whom I boght the battery.

Bucksy34 Posted at 2017-7-11 04:18
Thank you,
I've been looking through the logs from "black box" with DJI Assistant and didn't find anything wrong with the aircraft. In fact it is still running, motor and the mainboard are ok, booting up, but it signals there is someting wrong with the gimbal.
I'm talking with the resselers from whom I boght the battery.

Does the battery still work?   (I don't suggest flying with it, but if it still recharges and powers up OK then...)

Nigel_ Posted at 2017-7-11 05:02
Does the battery still work?   (I don't suggest flying with it, but if it still recharges and powers up OK then...)

nope, battery, at impact, bounced into a curb and was broken / deformed.
I kept it outdoors in the open air, because it eliminates a bad smell.
it's unusable