Hi everyone. Built my first F450 quad a few weeks back and it's been fun getting it together. I'm using APM 2.6 with uBlox 6 GPS/compass. I've done all the necessary calibration and setting selection required, and as a result my quad arms fine and starts up.

Well, 2 motors start up. The other 2 don't move. I have to do stuff like manually spin it or move yaw/pitch/roll to max positions in order to get them to spin. Once they start spinning though, they work fine and my quad flies beautifully.

But why is this happening? Ive crashed my quad a lot, so I don't know if the motors or ESCs are damaged. I've soldered the ESCs onto the PDB and motors are connected to the ESCs via 3.5mm bullet connectors. While soldering, one of the gold plates came off so I joined the + of one ESC to the + of another ESC and soldered both of them onto the same gold plate. Could this be the reason?
I've also noticed that when I run out of battery, my first cell is always the first one to go low while the other 2 cells still have .4V left in them.

I use a FS CT6B and I've calibrated the radio and ESCs many times, so that's not the problem. I can't really recall, but I don't think I had this problem when I flew my quad for the first time. I've crashed it many times since then so I guess I damaged some of the parts.

I built this as a college project (gesture control of quad) and I won't be able to complete my project if this happens. I need the quad flying perfectly in order to even attempt gesture control, and things aren't looking good

Would appreciate some advice on how to proceed, thanks.

FS ct6b dude i have same problem with that radio i think your quad yaws a little bit . I think two opposite motors on same cross arm are not spinning isn't it?

"While soldering, one of the gold plates came off so I joined the + of one ESC to the + of another ESC and soldered both of them onto the same gold plate. Could this be the reason?"

I think ,,,,, YES !!!!
Either The distribution of power is not uniform over here or soldering wasnt good enough or even both.........Get a power distribution board from Quadkopters.com Or create your own power harness...... And re try

But if you are having an extra esc try connecting the motor to it.....And test if that motor is working fine.
In my case i had extra frame...Which had power distribution.. So i soldered an esc to frame and connected my motor and receiver to it and unit tested the motor. This may help u...
If motor works fine then definitely its a problem with power distribution...!

Good Luck !!

Try connecting all 4 ESC's signal pins to one channel and give little bit of stick input and to check whether its FC problem or ESC's.

remove your props, re caliberate your ESC's again ( i hope u have done it)
bring your trims to neutral first.
then put your props and try flying it in an open feild.
tip : get a radio with digital trims,