Voltage regulator replaced but still not working

[Marmotta]

I've got a device that runs on USB VBUS 5V and sends 3.3V and 1.2V to the ICs on the board through a couple of regulators. However, the CY7C68013-56 chip is not being detected when inserted into my PC and on further inspection it seem the 3.3V voltage regulator has a 5V input and is connected to ground, but isn't outputting anything at all (note the 1.2V reg is working fine). I swapped out the regulator for another I had on hand, but the same issue is still happening.

I think I have a schematic of the board attached (or at least one that is very similar), any ideas what other components could be causing the regulator to fail? I've had a cursory look for shorts and didn't find any, but will check it over again, as well as see if the board will power up with 3.3V applied independently. 

[thm_w]

Could be a capacitor or IC shorted to ground on 3v3 output.
When you measured the 3.3V rail, resistance to ground was what?

As you said, next step can be injecting 3.3V, preferably start low and dial up the voltage, with a current limit of ~300mA. If current limit exceeded, poke around to see if anything is getting hot or if you can narrow down the short with voltage drop measurements.

[DavidAlfa]

If there was a short at the input, you wouldn't have 1.2V, so it must be at the output.
The LDO should be getting warm.
Check there're no solder bridges between the CY7C VDD/GND pins.