Identifying quiescent current source in low power module
As far as I can see your supply can either come from \$V_{USB}\$ or \$V_{BAT}\$. It is a bit hard to see the component values due to the image resolution, but I would guess the &quot;high&quot; quiescent current is due to the resistors to ground.
Roughly calculating the quiescent current due to the resistors connected to ground only, when supplying with the battery:
$$I_{BAT}=5V \cdot \left( \dfrac{1}{R_{18}} + \dfrac{1}{R_6 + R_7} \right) = 5V \cdot \left( \dfrac{1}{100k\Omega} + \dfrac{1}{430k\Omega} \right) \approx 61\mu A $$
and when supplying with the usb:
$$I_{USB}=5V \cdot \left( \dfrac{1}{R_{19}} + \dfrac{1}{R_12 + R_{13}} \right) + 4V \cdot \left( \dfrac{1}{R_{18}} \right)  $$
$$I_{USB}= 5V \cdot \left( \dfrac{1}{100k\Omega} + \dfrac{1}{69.6k\Omega} \right) + 4V \cdot \left( \dfrac{1}{100k\Omega} \right) \approx 161\mu A $$