My MacBook Pro 13 does not POST, no video at all. Diagnosis
Laptop: Macbook Pro 13 from 2010 with Core 2 Duo 2.66Ghz, 4GB RAM, 320GB Hard disk. Installed OS is Mountain Lion.
Symptom: Laptop powers up but does not post audibly and visually on the screen. But I can hear the SuperDrive spinning and the hard drive thrashing a bit, which indicates that POSTing may be happening but is not being displayed on the Screen. I could have proved this point if I had an external VGA adapter that can connect to the mini-DVI of the laptop. But did not have one. So, I had to try something different.
Diagnosticss: As usual, the first thing I did was try to have a bare minimum connection to the laptop's logicboard and then power it up. That is a trick I learned from old days when I used to troubleshoot Pentium IV motherboards. LOL. Back then, I would simply disconnect everyting to the motherboard, remove it from the case, rest it on top of motherboard box and leave it bare with only CPU, HS, RAM and video card, connect to a power supply and then I try to power it up. DISCLAIMER, PLEASE DO NOT TRY THIS TRICK. CAVEAT EMPTOR.
So, I removed the bottom cover of my Macbook Pro 13, then disconnected in order of singnificance the battery, and then every ribbon cable connected to the logic board, with the exception of the LED screen cable and the combo KB+power switch cable. Then I connected the charger to the laptop and VOILA! the laptop chimed its Big Ben and I can see video. So, which of the connected devices is causing this problem. i want to spare you the detail of my endeavor. it was the combo Airport Wireless Extreme card + Blue thooth + Antenna ribbon cable, which meanders from the LHS of the laptop at 90 degree angles until it connects to a port on the logcboard adjacent to the SuperDrive connetor.
On Macbook Pro 13, and Macbook Unibody Aluminum, the Airport Extreme Wireless card is located in the Screen Assembly at the base and covered by a black plastic enclosure that runs horizontal at the base of the screen when it is erect. This cable is for three components: the wireless card, bluetooth card, and the antennae. i am dumb founded as to how any one, or all of these components would interfere with the Display graphics system. Could it be a short in the cable, could it be a faulty chip, or the cable gone rouge?
If there is someone who did troubleshooting for a similar problem, please step forward and share your experience. You will be showered with my gratitude. :)