Hi guys... new to quads but I managed to build and get about 2 batteries worth of "learning to hover" on my first build.

On my last flight, though,  I was about a metre off the ground and the quad just dropped... when I reset and tried to re-arm it wouldn't do anything.

Unplugged lipo and back in and I on'y get the first (3?) tones from the esc's (not the last 2)... 
x6B receiver gets power and connects (solid light) to my flysky i6x

but taking the quad home I now see that there is no activity light flashing any longer when I connect to battery or usb.  Solid red light powers up (on USB connect) and solid blue and red lights power up with LIPO bu no flashing activity light at all.

And... my computer doesn't beep when connecting via usb to tell me it recognises the device.

All this indicates to me the FC is locked up (not dead as I can power it up and power through to the receiver).
I tried doing a firmware erase and flash but I can't connect to a serial port (according to betaflight).

Anyone experienced this and got out of it?  Will I need to get a new FC? It's an HGLRC F4 V5 Pro.

Any help would be great...
Thanks in advance. 

Danny

Your flight controller is dead. The facts that the ESCs don't give the second beeps (of which the first one means 'throttle signal detected' and the second one means 'throttle detected at zero, now armed') and that your computer doesn't recognise the USB connection both say that the microprocessor on the flight controller is not running.

Some pictures of how you put everything together would help us in advising you why this may have happened and how to avoid it happening again.

Thanks for your reply.

I'll get some pics up and running...

but I guess a new FC is in order....

https://imgur.com/7qFQTjZ

https://imgur.com/guhsIH4

https://imgur.com/mCQBdVg

https://imgur.com/kjZ4Svw

A couple of points.

In the first picture, I see a big lump of stray solder on the side of the electrolytic capacitor that you have added to the battery inputs. If the capacitor was on top of the flight controller, the stray solder could well have shorted something out.

Your soldering needs more practise and maybe a higher wattage iron. Many of the solder joints appear to be lumpy, as if the solder has not flowed properly.

Seeing as you have a problem with stray solder, go over the entire flight controller with a magnifying glass and make sure that there isn't a little ball of solder shorting something out.

You may have just been unlucky, but if the processor doesn't run and you don't see the normal LEDs light up, then the 3.3V supply to your processor and other chips is not working. That's either because there is a short circuit somewhere which is making the internal 3.3V regulator shut down, or the 3.3V regulator is faulty.

OK thanks unseen...

I accept that my soldering needs a lot of work. but I did take to the board with a multimeter to test for shorts and leakage.
But having said that your eye for detail is amazing... I totally missed that solder on the cap.

I'm going to have to remove the FC anyway so I might as well start cleaning up everything and removing as much solder as possible ready for the next FC.

Thanks again for your time in looking at my shoddy work...

Pictures are always better than 1000 words.

If there's a short on the board which affects the 3.3V circuitry, you won't see it with a multimeter on the power inputs as the short is on the other side of the regulator.

The best way to get better at soldering is to buy some hobby circuit board and use that to practice with. That way, you're not risking anything expensive to improve your skills. Of course, you can only do good soldering with good tools and a quality temperature controlled soldering iron with at least 60W is pretty much a requirement, along with good 60/40 or even 63/37 flux cored solder.

I always take lots of time to thoroughly inspect everything under very bright lighting and high magnification before applying power. You'd be surprised how many little balls of solder you'll sometimes find even on something that you haven't even taken an iron to yourself.

Good luck with the rebuild!

Just to add to what unseen said...before you power up, go over each solder joint with a magnifying glass and also check for stray wire fibers that might cause shorts. They might not touch anything at the moment, but add vibration and BOOM. {see photo below} I lost a FC because of this. 

   

Also, make sure you tin both the whole pad (you have some partially tinned pads) and the wire before you solder them together. Try not to press the wire onto the pad with the soldering iron, thus flattening it and increasing your chances of strays / cold joints.

If you struggle getting the solder heated and find that you have to apply heat for a long time, get yourself a higher wattage iron. Preferably an adjustable soldering station. Changing from a DIY cheapo soldering iron to a proper station was the best thing I ever did in this hobby. 

Sorry about your FC. I've also paid my fair share of school fees. It sucks, but once you get it right, its damn amazing!

Thanks guys... It's encouraging to get a better understanding on what I've potentially done wrong so I can NOT do it again... I will be back on the horse soon enough...

After having a think about it... I reckon unseen got it right with the solder on the cap. It was the last thing I mounted in readiness for an inbound FPV camera - the quad flew/crashed perfectly the couple of times I went up before but this latest round after installing the cap was the fatal round...