Macbook pro shutting down and will not restart since installing Yosemite

Hi dennisfromfernley,

Happy Thanksgiving! Try these key combinations to put your Mac to sleep. If the issue persists, try the troubleshooting suggestions below:

OS X: Using the power button - Apple Support
http://support.apple.com/en-us/HT201150

OS X: Saving energy with Sleep - Apple Support
http://support.apple.com/en-us/HT202824

How do I put my Mac to sleep?

To put your Mac to sleep immediately, do one of the following:

• Choose Sleep from the Apple menu ()
• Press the Command (⌘) Option and Media Eject key (⏏) simultaneously.
• If you’re using a Mac notebook computer, close its built-in display.
• Tap the power button on your computer.

OS X: When your Mac doesn't sleep or wake - Apple Support
http://support.apple.com/en-us/TS5357

Restore Defaults in Energy Saver preferences

You can reset Energy Saver settings back to the way they were when you first got your Mac. To do this, select the option "Restore Defaults" in Energy Saver preferences.

1. Choose System Preferences from the Apple () menu.
2. Click the Energy Saver icon in the System Preferences window.
3. Click the Restore Defaults button in the Energy Saver window.
4. If you are on a Mac notebook computer, click the Battery or Power Adapter tab to switch settings. Click the Restore Defaults button in both panes if needed.

Additional troubleshooting

If the steps above do not resolve your sleep-related issue, try these additional recommendations.

Reset SMC

The System Management Controller (SMC) is involved in managing power on your computer. Reset the SMC on your Mac if you are having difficulty sleeping or waking your computer.

Reset NVRAM/PRAM

Nonvolatile RAM (NVRAM)/Parameter RAM (PRAM) stores some power-related settings.Try resetting NVRAM/PRAM if you are having difficulty sleeping or waking your computer.

Test with external devices disconnected

Some external devices can prevent your computer from sleeping. Try disconnecting items other than your Apple keyboard or mouse from the built-in USB, Thunderbolt and Firewire ports on your Mac. If this resolves the issue, try reconnecting your external devices one at a time until you find the device preventing sleep or wake. Check the documentation that came with the device, or contact the device manufacturer for more information.

Try Safe Mode

Check to see if the issue still occurs when the computer is started in Safe Mode. If this resolves the issue, it could be related to a third party software item such as:

• a login item
• a startup item
• a third party kernel extension

Try another user account

Try creating another user account, or log in as guest. See if your computer sleeps and wakes properly from the additional user account. If it does, your issue may be related to one of the following:

• a login item
• an app open in the original user account

You can disable login items from the Accounts pane of System Preferences. Try opening only one app at a time in the original user account to determine which app is preventing sleep. If you isolate the issue to a particular app or login item, check its documentation, or contact the developer of that software for more information.

I hope this information helps ....

- Judy