Chosen Solution
Hi guys I’m having a horrendous problem. This evening I fired up my MBP mid 2012/15”, it started booting then halfway (I think this is where the GPU kicks in) I got a solid black horizontal bar 3/4 of the way up the screen and it won’t boot. Specs wise it’s the 2.3GHZ i7 8GB RAM Sandisk X200 ssd 512GB 1TB Seagate Fusion Drive in the caddy. It’s running HS 10.13.5 or 6 I’m not 100% on that. Cleared NVRAM and SMC, popped the ssd and tested it on my partner’s 13” 2012 mbp and it boots fine, also setup an HS USB Boot Drive which also does the same thing. Heres the thing, it beeps as normal, starts booting and when it’s frozen, pressing the Enter key still makes a “dong” sound as it would if I was in Sierra and pressed the wrong button on a prompt window. it looks like something is glitching out when the graphics cards kick in but I just can’t figure this out. I’m in a pickle because I’m currently on a Greek island with crap internet and a good 5-12 hours from the mainland. I think there might be a flag in verbose mode so I’ll try and get some photos to upload. does this issue sound familiar to anyone? I really need some idea as to what I’m dealing with much love alex Update (08/18/2018) I tried the shift key for safe mode, so far I have a very long load and the screen eventually goes off, the sleep light fades in and out but I have to restart to get a response from the screen. I’ll try target mode and get back to you, with whatever images I can as well. Thank you so much for having a look! Update (08/19/2018) So target mode lights up fine and I’ve got FireWire and thunderbolt icons bouncing around the screen. I’m on minute 10 of holding the shift key down 80% of the progress bar, I’m not holding much hope there. I don’t know if it’s pertinent but the recovery partition didn’t show up when I hit option, just my two drives
Lets try this restart your system with just your boot drive (SSD?) and hold the Shift key to get into Safe Mode, see if your systems starts up then. If not lets try restarting again this time go into Target Disk Mode holding the T key. We only want to see if the screen shows either a FireWire or Thunderbolt Icon. If it does then we know your issue is within the GPU logic. Reference: Mac startup key combinations Update (08/19/2018) Well not good ;-{ The Target Disk Mode test proves the Intel intergraded graphics services is working! But, the dedicated graphics chip is not! You’ll need a new GPU chip or just replace the logic board. The GPU chip is not easy to find (new) and I wouldn’t try a used one as the process of desoldering it will fatigue it. It also needs special tools to desolder the old chip and correctly solder the new chip. Very few shops have the needed gear. Here’s the process: Louis Rossmann - Replacing A1286 GPU
