Locating the backlight driver if your screen is "on" but too dark to see.
You can download a Service Manual for the Nokia 8.1 from platforms like Elektrotanya , which often includes assembly views and component placement. nokia 8.1 schematic diagram
Locate the battery connector (J3200) on the schematic. Step 2: Trace the BATT+ line to the main fuse (F2000). Check for continuity on the PCB. Step 3: After the fuse, the line goes to the PM660. Using the diagram, measure the main power rail (VPH_PWR). If shorted to ground, the schematic helps you find the culprit capacitor (C3204, C3207) by its reference designator. Locating the backlight driver if your screen is