Fail circuit with N MOSFET, what is wrong?
If camera connects to servo driver and/or motor driver in any way, that is likely your problem- you are switching the low side of the latter. 

A high side switch (lots of answers here illustrate the concept) uses two transistors- one if which would best be a p-channel MOSFET to switch the loads. 

Edit: From your comments, it appears that the (unseen) Arduino is the problem, and because of the low-side switch as I speculated. 

So, move over to a high-side switch and all will be well.