Replaced logic board but have unexpected shutdowns
Ok, so I purchased a replacement logic board for my MacBook Pro 11,3. Original MacBook Pro ran High Sierra.
Swapped the board, and rebooted... But it would not mount the internal partition, for some odd reason. So I had to reinstall the original OS (Mavericks) from scratch after reformatting the SSD.
I did a PRAM and SMC reset and reverted to using my 85 W original MacBook Pro Adapter. The battery is new (changed about a month ago from iFixit - also how I damaged the logic board while pulling on the iSight connector).
For some odd reason the computer now unexpectedly shuts down, without warning. I ran Apple test (everything was ok). But the shutdown never happens during OS installation, so I am a bit at a loss to understand what is wrong with this machine. Under Mavericks though, this does not seem to happen.
The machine goes directly to a black screen, but the backlighting still seems to work.
I am suspecting a faulty discrete board (which is not used by the installer, probably because it boots in a limited mode) and/or High Sierra reccurent but am at a loss to rule any other options.
Is this a good question?