Hi everyone,

I just ordered brand new T-Motor F7 HD FC. I was using analog version of that now decided to go for HD system. 
I have T-Motor 55 ESC. Without going any soldering, I just plugged ESC to FC which ESC was soldered and working fine. After I did my test ESC and FC was working fine. After I just plugged DJI O3 Air Unit, FC just stopped working. No led, no beep nothing. Tried USB connection but nothing happens. ESC gets warm but again no led or anything. I tried DFU but that does not work either. I'm pretty sure wiring between FC and DJI correct since I've got cable and checked all wires.

You can see the video: https://drive.google.com/file/d/1dOKGQVM...drive_link

Is there anyway to solve it?

At a guess you've killed the FC somehow. No USB connection is generally a bad sign on it's own. No lights on it is a worse sign when you plugged the lipo in. I'd send it back or get another one. Also buy a smoke stopper. Every bit of soldering you do, go over it with a jewellers loupe or microscope and look for any bridging. if not use a multimeter. Even if what you are plugging in has a plug, check the wiring against the FC wiring diagram. Not all leads are the same.

Someone else might have an idea for you, but it looks dead to me.