No light, no fan, no sound.
The charger or the port (we check those first), or a power rail down on the board.
We measure the charger before opening anything. Then bench supply: 0 A means an open circuit; a high, fixed draw means a short.
It depends on the model and on what we find inside, so we quote each repair individually. The diagnosis fee depends on the device, and you approve the exact repair price before any repair starts. If it can't be fixed, you only pay the diagnosis.