I've tried to upgrade the firmware on my Phantom 4 via DJI Assistant 2. Whilst doing that I accidentally unplugged the USB cable to my PC. After reconnecting the cable the upgrade status stuck at 32% and didn't go on from this point. Now, if i turn on the Phantom it gives this constant beep noise. No lights under propeller. It's altering it's sound pattern from two to three to four beeps in a row. It drives me crazy. Here's what I already tried to solve the problem: - Factory Reset via DJI Assistant 2 -> failed saying "Factory Reset Failed!" - tried to downgrade to two different versions via DJI Assistant 2 -> always failed after download was finished - tried to upgrade via DJI Go App -> it said "your firmware is incomatible - reload the firmware?" -> I clicked yes and nothing happened after that - left the unit on for 45 minutes without being plugged to anything (since I read this works with the Phantom 3) -> beeping sound altered but nothing happened either I'm so desperate with this. How can I stop it from beeping and regain a working firmware?? Please Help!