Re: Turning off n-MOSFET
With an N channel MOSFET:
A) The drain must be at a higher voltage (i.e. more positive) than the source.
B) To switch it on, the gate must also be more positive than the source.
I don't understand how your circuit is supposed to work.
The drains of Q1 are connected to the anode of a diode, so they will never conduct any current. Q3 is connected as a source follower, so if there is a positive voltage on VAC_AdapterDC, then there will be a smaller positive voltage at TP14, but there is nothing to pull that voltage down. Q2 might conduct current from VCC to VAC_AdapterDC, depending on the voltage at TP13.
Maybe you want to supply current to VCC from either VBATTERY or VAC_AdapterDC. If so, you should be using P channel MOSFETs.