HP ProBook 4520s boards are serviceable with standard laptop-repair practices: careful visual inspection, systematic power/rail checks, and isolating components. For many common faults (battery/charging, HDD/SSD, RAM, display cable, fan), simple replacements restore functionality. For BGA-level CPU/GPU failures, reflow or board replacement is generally required.
: Checking the LVDS connector pins for backlight voltage. hp probook 4520s boardview