I had this same problem.  It would fly some time then start droping suddenly, sometimes if i do not push it up constantly it would drop on ground. I thought its a sensor problem, then battery problem (as i tried changing battery and sometime it would fly with no problem, but then when same battery is placed again problem would persist) i tried reseting, updating firmware for everything, but nothing coul help.
.... then i changed propellers ... at a time i used 3th party fancy transparent propelers, that was working for a while but got worn out or damaged ... placed original propellers again and it works all fine

markol Posted at 2017-7-2 05:40
Has anyone else had this issue? I'm just worried it's a hardware problem...

I know the reply is late. I came across a thread with the same issue, there are quite a few people with such an issue,

SaleKlar Posted at 11-6 03:00
I had this same problem.  It would fly some time then start droping suddenly, sometimes if i do not push it up constantly it would drop on ground. I thought its a sensor problem, then battery problem (as i tried changing battery and sometime it would fly with no problem, but then when same battery is placed again problem would persist) i tried reseting, updating firmware for everything, but nothing coul help.
.... then i changed propellers  ... at a time i used 3th party fancy transparent propelers, that was working for a while but got worn out or damaged ...  placed original propellers again and it works all fine

For me, he did the same with the original accessories.
Many people already believed that it was solved one way or another but in many cases the problem returned.
read this: I would recommend my theory to you. Mine did the same, once all the propellers broke because it landed roughly, in just I pushed the stick up. I managed to fix mine: https://forum.dji.com/forum.php? ... &extra=page%3D1

Jakab Gipsz Posted at 2020-11-13 13:38
For me, he did the same with the original accessories.
Many people already believed that it was solved one way or another but in many cases the problem returned.
read this: I would recommend my theory to you. Mine did the same, once all the propellers broke because it landed roughly, in just I pushed the stick up. I managed to fix mine: https://forum.dji.com/forum.php?mod=viewthread&tid=220364&extra=page%3D1

ah, i found this thread again after two years. Thanks for response lol. Anyway, i fixed the problem back then by remounting original propelers   I used some colorful propelers from aliexpress and for a while they worked fine, but then SPARK started acting crazy. I can just asume they produced some vibrations that spark could not handle.