Take off motor problems

When I try to take off my 450 Quad, Pixhawk, Firmware 4.2rc2, the motors seem to be lacking revs. then all of a sudden they speed up and the Quad shoots up in the air. I shut down the throttle to get control of it. Stop it crashing.
I’ve attached the Bin file. Looking at the RCIN and RCOT there seems some strange goings on.
Can anybody please have a look to tell where to look for this in my setup

a class=“attachment” href="/uploads/default/original/2X/5/553fe8712691ace14110e3aef6e6b0ca927c290b.bin">2016-11-13 13-40-38.bin (654.2 KB)

how do I attach a log ?

What flight Mode are you flying in?

If it is not Stabilise then the effect you are seeing is expected.
Remember, in pos hold or loiter throttle stick down means descend so the copter ends up with a negative altitude and won’t take off until you are above centre and it has come back up to ground level.

Try in Stab mode and see if the same thing happens.

I’m in stabilise mode.
I am using a replacment clone Pixhawk to replace a 3DR pixhawk. that failed to boot up. When using USB it reported low battery, even when there was no battery connected.

These are the log outputs of RCIN and RCOU