Dear,
I can’t connect my board through USB cabel (there is a solid green light, but nothing happened). Before that I tried to connect leds to the board and I think made a short circuit (mixed the cabels). I tried to measure the LDO on the board (5v to 3,3V) and they are OK. Is there something else that I can do?
Did you enabled DFU mode to flash the Fc with zadig ?
Before that, It works, so I think it something wrong with the board and I have to change some resistor or something?
So it worked at some point?
Yes it worked. Maybe I short circuit the board?
Is it possible that you flashed a wrong firmware ? 
No I think it is not possible, I can try it to flash again?!, but before that it works, than I tried to connect leds and than this happened…
arh…
Many you shorted something when connecting your LEDS and you have damaged one of the regulators.
Ok thank you, can you suggest me some good and cheap board (like this) Betaflight…thank you for your help
I can recommend the Omnibus F4 v6:
Yeah as @Luca suggested the omnibus F4 is probably the best cheap FC so it will probably be best to just get a new one.
But for your old one, when you connect via USB does the MCU get hot? If it does then it definitely has a problem and will need to be replaced
So I have the same problem. Solid green light when I plug in usb and there is no sound of connection. For me I flashed the wrong firmware. I flaished Omnibus instead of Omnibus SD. What should I do is this something I can fix??? … Zadig doesnt even see the stem3 driver. and beta flight doesnt even detect any com ports. I have tryed just about everything. its like the usb connect is not detectable. did me flashing the wrong firmware screw up my omnibus f4 v5 ?? do I need to buy another?
if you have loaded the wrong driver only and now wont boot do this. plug FC in computer first with BF running then click link and run.
you should now see DFU mode where com port should be.