ic desing working in spain
Let's assume that you have a regulator like the one shown in the attached chart.
You are forcing vref externally, vout is wrong and there is current consumption. As you can see, if the error amp is not working, there is an output transistor that could be in linear region, so you get the resistor between vdd and gnd.
Use the values of R1 and R2: Measure the voltage at vout and calculate the current through the output transistor, then knowing the dimensions, check if it is in the right OP.
Also the current through vdd minus the calculated current through output transistor equals the current consumption of the error amp. Is it correct?
There is not much you can do with only those pins, so, check the currents and try to find out if the circuit is on or not.
BTW, do you have some kind of oscillation? maybe low-freq? Try changing the value of the external cap (important also the ESR value) to see if it is a stability issue