Measure their resistance to ground. The 3.3V rail should ideally read in the kilo-Ohms. If it reads under 10-20 Ohms, you have a short circuit.
Websites like Maruti IT Experts or specialized repair forums (like Badcaps or EEVblog) sometimes provide access to these schematics. ms-16j91 schematic
These voltages switch on only after the power button is pressed. The +1.2V rail powers the DDR4 RAM modules, while the "Run" variations power peripheral controllers, the audio chip, and local LAN hubs. 4. Core Rails: +VCC_CORE and +V_VGA Measure their resistance to ground