Chosen Solution

Hi, I’m trying to see if I can narrow the problem down any further; I suspect a logic board or heat sensor. My laptop was running on battery, I left the room, and when I came back a while later it seemed to have gone to sleep. I pressed a key to wake it up and it made disk drive startup sounds but nothing else; the light on the front was still pulsing. I figured the battery was low, so I plugged it in and the battery charged up fully according to the battery lights, but the computer still wouldn’t wake up so I powered off. Now, if I try to turn it on, the fans and drives start spinning and then the whole thing just shuts down within about a second (it sounds as if you had held down the power button to shut off). There was a DVD in the drive but I couldn’t even coax it into ejecting so ended up opening the drive case to remove the disc. I’m pretty sure they replaced my main board when I brought it in for a display replacement a couple of years ago (the board qualified for replacement because of an NVIDIA GPU issue I think). If I remove both DIMMs, I get a repeating single beep indicating no RAM — it seems content to run like this for ages. If I hold down the power button, it will stay on until the front light starts flashing rapidly, which I understand means it’s looking for a firmware update, and then immediately turns off. Other than that, I have tried: resetting the NVRAM (no change)resetting the SMC (no change other than faster spinning fans on the next boot attempt)swapping and removing DIMMs one at a time (no change)individually disconnecting each of the connectors (drives, sensors, fans, etc.) on the logic board and trying to boot; nothing of note except:* I didn’t disconnect the keyboard connector, since I couldn’t turn the power on in that case* with the the left I/O board connector off, the machine doesn’t do anythingtrying A/C only, battery only, and both (same behaviour in all cases) Does anybody have any other suggestions to narrow the problem down or a confident sense whether it’s the logic board or not? I’m a bit thrown by it’s ability to sit happily beeping with no RAM in. Thanks!

AFAIK it’s standard to beep RAM missing/failed - there’s no automagic shut down for failed RAM.. but without RAM the boot process can’t finish. If this answer is acceptable please remember to return and mark it.

Hook it up to an external monitor and see if it is generating a video signal.

Hi all, I just got this problem as well. I recorded a video and post it on YouTube Any help with this issue guys ? https://www.youtube.com/watch?v=3Iwbf6xy…

On the left I/O board #820-2273 you will have three fuses. On the back side of the board 2 each on the upper side consequently one. These are called SMD fuses, F9800 and F7902. Color White. On eof them is pretty small. The best way to look for them is removing the Black feel off after you removed the four philips screws. The other fuse is located on the upperside close to one of the output connectors.

Turn on macbook when you hear the chime… press the mousepad in with one finger and hold until computer fully boots. Just worked for me.