Backlight vs no-image: flashlight test and what to measure next

Display split that saves hours (NLCRC paraphrase of a classic laptop display teaching point). Flashlight test - Dim image visible under a bright light → image path partly alive; chase backlight enable / boost / LED string. - Truly black with no silhouette → eDP/LCD power, cable, panel, or GPU/PCH output. Measurements that matter - Panel main voltage during the power-on window. - Backlight enable and boost output (careful — high voltage on some designs). - External display: if HDMI works, stop blaming “dead GPU” for an internal-only fault. Cable / panel - Reseat LCD cable both ends; try a known-good panel when you can. Post board PN, flashlight result, external display result, and any panel voltages.