Need help on troubleshooting PCB circuit
This design was poorly done.  The wrong FET polarity was chosen for a high side switch and is not even needed.  There is an EN(able) logic level not being used .  


remove FET and jumper across Drain to Source and 12V should then be working. If so , then 
cut EN track and jumper to Q or Gate pad.
cut Vdd also on U1 and connect to Vcc track on U2 which is needed to make EN work.
keep U1- En,Boot &amp; Vdd together but cut from Vout and connected to U2-Q out to enable if it ~5V.
as said in comment the LED is misplaced and never belongs there.


There may be other issues.

“The correct C3 capacitor for particular input and output voltage values cannot be calculated. Choosing the correct C3 capacitance is best done by trial and error, in conjunction with the checking of the inductor peak current to make sure your not too close to the current limit of the device. “

This is a perfect example of a time to scrap this effort which can be corrected but needs experience and order something from amazon or equiv.