System information

Mac mini (Mid 2011) Take Apart — General Troubleshooting 15
2011-07-21
Logic Board Reset - Coin Battery Test and PRAM Reset
A dead battery may prevent computer from operating. Removing the coin battery for 1-2
minutes will also fully reset the logic board PRAM.
1. Shut down and unplug the computer. Allow several minutes for power supply to discharge.
2. The coin battery is located on the bottom side of the logic board and provides power for
the battery-backed RAM and clock. Measure DC voltage on battery touching battery with
red probe, and grounding with black probe. If voltage is 2.7v or less, replace battery.
3. Reinstall battery and reassemble computer.
4. Power on computer.
5. If computer starts up successfully, check for and apply the latest software and rmware
updates.
6. The coin battery removal also resets the date and time: use the Date & Time pane of System
Preferences to adjust back to actual date and time settings.
Starting Up in Safe Mode
A Safe Boot is a special way to start Mac OS X when troubleshooting. To start up into Safe Mode
(Safe Boot),
1. Make sure the computer is shut down.
2. Press the power button.
3. Immediately after you hear the startup tone, press and hold the Shift key.
Note: The Shift key should be held as soon as possible after the startup tone but not
before.
4. Release the Shift key when you see the screen with the gray Apple and progress indicator
(looks like a spinning gear). During startup, ”Safe Boot” appears on the Mac OS X startup
screen. To leave Safe Mode, restart the computer normally, without holding down any keys
during startup.
For more information refer to the Apple Technical article:
HT1564: Mac OS X: What is Safe Boot, Safe Mode?