Oneday after upgrading new motors, or from small crash, or just nothing... you got it issue and you cannot start motors for flight. There are no Official DJI Store at my place, so If I want to repair I have to send drone back to China and wait for 60 days. So I tried out and fixed it myself with 3 things to consider, just step by step, it took almost 3 days working for all test. Conclusion: Check all the connection.
All Errors I meet by each test:
Propulsion systems auto check Error (1 or more)
ESC Error
Battery Installation Error
Battery Connection Error
0 percentage Battery on OSD
Downward Vision Sensor Error
Vision System Connection Error
Flight Controller Fail To Start
GPS Error

Thank you.

Hi Lucas Tran, we are sorry to know about the crash. We do not recommend that you repair the drone on your own, which may cause safety issues and affect the warranty. You can contact our support team through the link below for further assistance. http://www.dji.com/support

Interesting to see!

Very nice DIY fix.  Also kept you from being without your Avata for almost 2 months.