Chosen Solution
It is the 2.66 GHz Core i7 model. I say it is not the OS because it crashes with two different OSX boot disks and during OSX recovery mode. Have tried the following: Sent it to a shop to have the bad capacitor on the logic board replaced. I previously had the capacitor overheat issue but the symptom was different: under GPU load the laptop rebooted. The current symptom is a complete power down: it never powers back up to show a panic screen.Booting with each of the RAM sticks one at a timeNVRAM clear and SMC reset startupsSingle user mode (runs for 30s or so before shutting down)Verbose mode: shuts down during a different log message each timeSafe mode: typically gets to login screen then shuts down shortly afterRecovery mode: shuts down a few seconds into the recoveryReplaced the hard drive with another OSX drive: same symptomsReplaced the hard drive with Windows bootable drive (boot menu then BSOD)Target disk mode: stays up as long as I want it to be upSearched for panic files while in target disk mode: found recent startup logs but no panic logsRan Apple Hardware Test: quick test and long test passedFroze computer in freezer for one hour: shut down in same amount of time during bootBoot from High Sierra installer USB stick: shutdown during boot What I have not tried: Repaste the heatsink (ordering paste today). I live in a dry climate which might aggravate heatsink paste drying out?Remove battery One frustrating thing is that ifixit.com has a procedure for replacing the heatsink paste but does not describe the symptoms that would lead you to execute that difficult procedure. Obviously if you can run the laptop long enough to read temperature sensors you would know it was overheating. Does overheat shutdown occur before the system would record a panic? FWIW, this question is similar to: MacBook Pro turns on, shows Apple logo or desktop, and cuts out.
I sent this laptop to a second shop for repair. They told me the logic board was ok but the keyboard was bad. They said the first indication of the keyboard failure was no response to the brightness keys. In the 30-60 seconds that it would run I never noticed a problem with the keys but never tried to adjust the brightness. After the repair, the laptop works normally: and the cap overheat Nvidia GPU problem is gone, due to the repair from the first shop. @Dan has been trying to work out a model for the root cause. It seems that as heat (or charges?) built up it triggered the keyboard failure: some short or false button press combo that led to shutdown. It is interesting that target disk mode and AHT were able to keep running. My guess is that either they don’t activate the keyboard the same way or they don’t generate enough heat to trigger the failure.
First Target Disk Mode uses the the Intel Graphics engine Vs the NVIDIA GeForce GT 330M GPU and it still uses the CPU for either, granted its not heavy taxed. So that is a very powerful diagnostic clue! With the rest of your symptoms it’s clear the NVIDIA GPU is failing. Here’s a good write up on the issues with the NVIDIA GPU Cures for a panicking mid-2010 MacBook Pro sadly Apple pulled the Tech Note HT203554 which offered more information. There really isn’t anything else you can do other than replace the logic board. Update (11/14/2020) Let me re-phrase… If you have already replaced the cap, then you need a new logic board to get the NVIDIA GPU working, otherwise you’ll disable it which in this series really limits the graphics performance as the Intel HD graphics engine is not very good. The 2011 boards have the AMD Radeon HD 6750M or 6770M GPU and Intel HD Graphics 3000, the 2012 model has the NVIDIA GeForce GT 650M and Intel HD Graphics 4000! The root issue is people push the graphics with newer more powerful apps which this series was not expected to run.
