No Power No Video
The computer will not power on (no sleep light, no fan movement, no hard drive spin-up, no Caps Lock LED illumination when pressed, and no display illumination).
Note: After each step, check that the system is not supplying power to the logic board. If you see the sleep LED come on or the Caps Lock LED illuminate when the key is pressed, then the system is indeed drawing power. In this case, hold down the power button for six seconds to insure the system is shut down before working on the machine. At this point, the issue is no longer a "No Power, No Video" problem. Move on to the Power, but No Video troubleshooting section.
Note: Examine the display carefully. An image may be barely present on the screen, but with no backlight clearly illuminating the image. In this case, the system is working properly except for the backlight. Use the Display:Dim Video troubleshooting section to resolve this issue.
- Remove any connected peripherals and eject any ExpressCard.
- Check that the battery has enough charge to start the computer by pressing the button next to the LEDs on the battery (on the bottom of the machine). At least one LED must light solid (not flashing). Make sure the battery is fully seated.
- Connect a known-good Apple 85W Portable Power Adapter and power cord or plug to a known-good power outlet. If the DC plug is properly inserted, the LED should light up; if not, go to the MagSafe connector troubleshooting section.
- Try powering up without the battery installed. If it boots, try a known-good battery. If it does not boot, replace the battery connector cable.
Note: With the MacBook Pro (15-inch Early 2008), unlike previous models, if you use the MacBook Apple 60W Portable Power Adapter to power the system, the battery will need a minimum charge to be able to boot the system. If the battery is fully depleted and no 85W adapter is available, allow the battery to charge first before turning on the system.
- Reset the SMC (power manager) as described in "Resetting the System Management Controller (SMC)" under "Troubleshooting Tips and Tricks" in the previous section.
- Try to power up the system and check the sleep indicator. If it turns on solid and turns off, the main logic board is getting power and completing the boot cycle. Go to the Power, but No Video troubleshooting section.
- Verify that the power button cable is connected properly to the top case flex cable assembly and that the flex cable is connected correctly to the logic board. Try turning on the system.
- Disconnect the keyboard completely. Inspect the connectors. With the keyboard disconnected, restart the system using the on-board startup jumper pads. If it boots, replace top case.
- Remove any additional RAM.
- Try removing the AirPort Extreme card from its socket and start the computer. If it starts, shut it down and check the flex cable connector and the connector on the logic board and replace the damaged parts.
- Re-seat these flex cables:
- Left I/O flex cable
- Hard drive flex cable (will boot to flashing folder if not connected or corrupt)
- Optical drive flex cable
- Trackpad flex cable
- Display LVDS cable
- Thermal sensor cables
- If the computer starts up, inspect any suspect flex cable connectors and their terminals on the logic board for damage and replace any damaged parts.
- Replace the left I/O board.)
- Replace the logic board.
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