I found that model 177 has a 6-leads SOT-23 with name LPTZ, follow you guide, i check the pin 6 to COM, it's on a rail; then measure the impendance of pin1 (GND) - Pin4 (Vin) is high ~ 5MOhm; pin 1 - Pin 6 (Vout) ~ 30KOhm (infact the impendance is not stable at a value, it varies). So, it's the sign of defect the LPTZ component?
Looking forwards your early tip to bring it back normally.