The LED part of any true bypass pedal build is really simple. Essentially you have +ve voltage supply, LED, a resistor, a switch (usually one part of a 3PDT stomp switch) and ground. The resistor can be on either side of the LED, as can the switch. The only thing stopping the LED from lighting would be that it is installed backwards, The switch is broken (they can be a bit fragile when heated so soldering can do it if you aren't careful) or there is a poorly made solder connection in that part of the circuit. Test it all with a multimeter set to either ohms or continuity with no power to the circuit.
