'''Update 2:''' The paper clip worked, but if I ever closed the lid, I had to expect it to be shut down when I opened it again. Note: what actually solved the problem was the Security Update 2019-005 for macOS 10.13.6 that I installed a few weeks ago. No joke, it’s been running perfectly fine since then, without a single random shutdown. Not coincidentally, I remember the problem first started after the previous Security Update 2019-004 installed itself. So this is on Apple.
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'''Update:''' Never mind, it’s acting up again. Time to look for a new MacBook (it has other issues too, e.g. with the battery, and the left shift, ctrl, and option keys don’t work, and it’s just really old). In the meantime, I’m now trying the “paper clip crammed into the eject button to hold it down” trick.
'''Original comment:''' I had the same problem with my MacBook Pro (13-inch, Mid 2010). Sometimes it would shut down without warning. Sometimes I saw, "Are you sure you want to shut down your computer now?" Sometimes it would shut down during startup (holding down any key made it start up completely).
I tried the same solution as above. Opened the back panel and disconnected the battery. Found the keyboard ribbon cable and the ZIF socket (see step 11 in the guide linked above, in Scott Blinman’s answer). Lifted the socket hinge and carefully removed the ribbon cable.
Cleaned the ribbon cable and socket with Q-tips and rubbing alcohol. Blew out a few crevices and lightly dusted the logic board with clean Q-tips. Reinserted the ribbon cable. Reconnected the battery, screwed the back panel into place, and hit the power button.
It started up without holding down any key, and I've been typing this whole response without a hiccup. No need to replace the entire logic board, this did the trick!
I had the same problem with my MacBook Pro (13-inch, Mid 2010). Sometimes it would shut down without warning. Sometimes I saw, "Are you sure you want to shut down your computer now?" Sometimes it would shut down during startup (holding down any key made it start up completely).
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'''Update:''' Never mind, it’s acting up again. Time to look for a new MacBook (it has other issues too, e.g. with the battery, and the left shift, ctrl, and option keys don’t work, and it’s just really old). In the meantime, I’m now trying the “paper clip crammed into the eject button to hold it down” trick.
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'''Original comment:''' I had the same problem with my MacBook Pro (13-inch, Mid 2010). Sometimes it would shut down without warning. Sometimes I saw, "Are you sure you want to shut down your computer now?" Sometimes it would shut down during startup (holding down any key made it start up completely).
I tried the same solution as above. Opened the back panel and disconnected the battery. Found the keyboard ribbon cable and the ZIF socket (see step 11 in the guide linked above, in Scott Blinman’s answer). Lifted the socket hinge and carefully removed the ribbon cable.
Cleaned the ribbon cable and socket with Q-tips and rubbing alcohol. Blew out a few crevices and lightly dusted the logic board with clean Q-tips. Reinserted the ribbon cable. Reconnected the battery, screwed the back panel into place, and hit the power button.
It started up without holding down any key, and I've been typing this whole response without a hiccup. No need to replace the entire logic board, this did the trick!
I had the same problem with my MacBook Pro (13-inch, Mid 2010). Sometimes it would shut down without warning. Sometimes I saw, "Are you sure you want to shut down your computer now?" Sometimes it would shut down during startup (holding down any key made it start up completely).
I tried the same solution as above. Opened the back panel and disconnected the battery. Found the keyboard ribbon cable and the ZIF socket (see step 11 in the guide linked above, in Scott Blinman’s answer). Lifted the socket hinge and carefully removed the ribbon cable.
Cleaned the ribbon cable and socket with Q-tips and rubbing alcohol. Blew out a few crevices and lightly dusted the logic board with clean Q-tips. Reinserted the ribbon cable. Reconnected the battery, screwed the back panel into place, and hit the power button.
It started up without holding down any key, and I've been typing this whole response without a hiccup. No need to replace the entire logic board, this did the trick!