Sounds like something might not be right, did you order the kit from us? Otherwise could you send a photo showing the problem?
i just bought a ZMR250 off a buddy im not to intelligent with drones an cant arm it or figure out how to connect to librepilot, im on a mac an cant find anything for macs. when i try to connect it to libre pilot the usb dosent show up i have already flashed with cleanflight.
Hi
If you have already flashed it with cleanflight, that is probably why it cant connect to liibrepilot software. Are you able to connect correctly to the board with the cleanflight GUI?
"the way the propeller nut unlocks is the direction the motor should spin"
This is not correct.
basically, if you can fasten the prop nuts clockwise, then you have a CW motor or prop shaft.
If you have CW motor, get the Right handed thread nut (standard thread).
For CCW motors, go for left hand thread nuts (reverse thread)
Sorry Erkut, but you’ve got it the wrong way round.
If the prop or rotor is turning CCW then the nut must tighten CW (or a Right Hand thread), and vice-versa.
If you do it your way, due to the torsional forces involved, there’s a possibility that the prop can ‘unwind’ the nut, and throwing a prop, even a 5" one, is a scary event.
I think the main cunfusing problem is where we look at the motor, rear or front.
If you define CW rotor as which rotates CW when you look from rear of the motor, it is ok. Then, it will rotate CCW, when we look at front (into the paper).
I’ve never seen motor rotation described looking at the rear, it’s always been described looking at the front of the motor.
hehe, we have to come back to the roots of beeing in air… 
not so long ago airplanes could only stay in air if a real human was sitting inside controling it.
Their view sitting behind the engine was the main view they had and this was looking form backward into the propeller.
If you are having your model infront of you looking down to your motor. it truly sounds unreal why the hell did someone flipped arround the directions. But its where things belongs to in this case. The brave man was sitting in his seat starring infront of his propeller out of the sky.Even if this makes our world alittle wired 
My 13 YO son and I have followed your helpful guide with slow but steady success. The QAV ZMR250 bought from UnmannedTech is built, flashed with latest firmware using LibrePilot Vehicle Setup wizard. We can start up motors 1,3,&4 but unfortunately my CC3D does not fire output 2. All four motors will work on outputs 1,3,&4. Using Libre Pilot, I have tried to use output 5 to fire motor 2, through the vehicle tab. Initially I could fire motor 2 using the slider on the output tab. But when I used the remote to control the motors, only 1, 3, &4 fired. Now I can no longer control motor 2 using the slider. Although output channel 5 is allocated to Motor NE, I cannot move the slider anymore. Any suggestions please? All help gratefully received! This was my son’s birthday present on 4/10/16, and he’s getting a bit twitchy now as it still hasn’t flown…
Have you downloaded the correct drivers? You should have two drone specific drivers downloaded. I’m sorry I don’t know their exact names, but with a little bit of research they should show up online
Thanks for all the free knowledge Dronetrest! Quick Question(s)… Does everything look compatible with one another in this list (hardware and software? Should I upgrade the receiver that comes with the transmitter ( FPV will be installed after successful build) ? Any connectors/ wires i should have before i start?
Frame Kit- Carbon Fiber Mini 250
Motors/ ESC kit- RHD 22042300KV / Blheli 20A Mini
PDB- CC3D BEC 5V 12V LED Switch PCB
Flight Controller- CC3D EVO (OPEN PILOT)
Propellers- Gemfan 5030
Transmitter/ Receiver- Turnigy 9x/ 2.4gHz 9X8C V2
Battery- Tattu 3S 1550mAh 11.1V 75C 3S1P with XT60
Hey it seems like the two ESC to motor pictures in the written guide and Flight Controller video contradict themselves? Can you please clarify to me the correct ESC to motor configuration for CW and CCW motors? I’m having trouble calibrating and I think I might have the connection configured incorrectly.
This build guide works a treat. Total newbie to drone building and this guide got me through it in no time.
Here’s a vid to prove it works.
Also, the service from Unmanned Tech is fantastic.
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Congratulations on building your first quad! And not crashing on the first flight! 
Super useful guide. I dont have a USB cable included in my kit. Is it just a mini USB?
Yeah.
Mini USB fits, most if not all boards.
Thanks for the great beginner guide. Finally finished a very similar build. I was wondering about the 5v power source for the flight controller. Is having all 4 5v power connectors connected from the ESC’s OK or is only one of the ESC’s actually providing power? Thanks again.
I’ve heard its ok and the FCs can take it…
But then its always been recommended to me to only connect one and not put the extra power into the FC if its not needed.
So my advice would be just to have 1 5v input powering the FC
This is an interesting point as I agree most FC can handle this now days. But if your ESC use a switching regulator they can actually cause some interference with one another and result in a voltage brownout which can cause the voltage to drop below 5v momentarily, causing the FC to turn off.
Good this is that nowadays 99% of ESC used for quadcopters use linear regulators so this is not a problem. But it’s always better to rather only have one power source for your fc