Help with P channel FET not turning off
As @Frog said, when the output of your microcontroller is at 3.3V and the supply voltage is 3.6V, \$V_{GS}\$ for the MOSFET is 0.3V. So, the MOSFET is not completely cut off.
If your 3.3V is actually a bit less than 3.3V and/or your 3.6V is actually a bit above 3.6V (a fully charged LiPo battery?) then the situation is worse.
You need to add another switching devices, such as an NPN or NMOS transistor, that can be controlled by the microcontroller while allowing the PMOS gate to rise all the way to 3.6V.