I downgraded AC firmware to 1.7.0.90 and RC firmware to 1.5.8
because after the latest firmware update(1.8.1.00), "No signal" happened so often during flight so that I couldn't finish a job in front of many clients.
After came back home, I tried downgrading the firmware of AC/RC but when downgrading RC firmware in DJI GO app, after 99% of progress and the last long beep sound, it displayed "upgrade failed" (which means actually downgrade to 1.5.8) (My tablet is Nexus 7 2nd with Android ver.6.0.1)
So, I tried a mannual update method with a USB memory stick. But nothing happened when plugged USB stick. And when I rebooted the RC, there was no booting melody with white light in the first LED on.
I tried downgrading again in DJI GO app, but the same happened (at 99% with finishing beep sound and "upgrade failed" displayed)
And from that time on, whenever I boot RC, the red light flickers in the first LED with strong emergency beep sound.
When I get into downgrade screen of DJI GO, it goes like this:
-- Firmware version: null
-- No available firmware to downgrade
When I click overall status, it goes like this:
-- Remote controller FPGA error
-- Hardware malfunction. Contact customer service for repairs.
I guess this must be a firmware corruption. How can I fix this?
I can't send my RC for repair because I have jobs scheduled next week. How can I initialize the RC firmware?
Thanks.

because after the latest firmware update(1.8.1.00), "No signal" happened so often during flight so that I couldn't finish a job in front of many clients.
After came back home, I tried downgrading the firmware of AC/RC but when downgrading RC firmware in DJI GO app, after 99% of progress and the last long beep sound, it displayed "upgrade failed" (which means actually downgrade to 1.5.8) (My tablet is Nexus 7 2nd with Android ver.6.0.1)
So, I tried a mannual update method with a USB memory stick. But nothing happened when plugged USB stick. And when I rebooted the RC, there was no booting melody with white light in the first LED on.
I tried downgrading again in DJI GO app, but the same happened (at 99% with finishing beep sound and "upgrade failed" displayed)
And from that time on, whenever I boot RC, the red light flickers in the first LED with strong emergency beep sound.
When I get into downgrade screen of DJI GO, it goes like this:
-- Firmware version: null
-- No available firmware to downgrade
When I click overall status, it goes like this:
-- Remote controller FPGA error
-- Hardware malfunction. Contact customer service for repairs.
I guess this must be a firmware corruption. How can I fix this?
I can't send my RC for repair because I have jobs scheduled next week. How can I initialize the RC firmware?
Thanks.

