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Macbook pro won’t start even with external bootable harddrive . Chime could be heard upon switching on ,then goes to sleep …sometimes it gets on but stuck at apple logo while booting … please help
The following below does not apply to the A1502 13” Macbook Pro Retina so ignore this answer. When it works does it stop working after putting the Mac to sleep and waking it up? Closing and opening lid for example. It sounds like the graphics mux chip needs to be reflowed and desoldered. Note that this is not a graphics chip but a chip behind the ball that tends to get loose soldering due to its placement and lead free solder. Resoldering with leaded solder will fix the connections on that chip and fix the problem if it is being caused by that. A reputable MacBook repair store that does micro soldering should be able to fix this for you. Edit: The chip I am referring to is U8900 for the graphics mux chip that provides voltage to the GPU.
You’ll need to disconnect the battery following this guide to Step 6 MacBook Pro 13" Retina Display Late 2013 Battery Replacement. with nothing plugged in press the power button holding it for a good minute. Then carefully place the system on its side so you can plug in the MagSafe charger and can see the internal display. Did system boot up on its own and show the Apple logo and progress bar?
