Hi,
looks like there is a switched-mode power supply missing, most likely a buck-converter. U19 is might be some kind of "Simple-Switcher" (Texas Instruments), which incorporates the switch. I assume you have tried to power up the boad with 5 V connecting to Vcc? From the top side it seems there is no connection between Vcc and the zero Ohm resistor R18 (output of the buck-converter?). So if there is no connection on the bottom side, your electronics will not be powered. Please use a multimeter to check if a connection between Vcc and R18 exist, and also between Vcc and the supply pins of the ICs as well between the R18 and the supply pins. Depending on your measurment results, you may create a connection by means of a wire between Vcc and R18, but check the maximum voltage rating of the components on the board as