Macbook PRO сброс PRAM и NVRAM

Выполнение сброса NVRAM/PRAM
1. Выключите ваш компьютер Mac.
2. Найдите на клавиатуре следующие клавиши: Command (⌘), Option, P и R. На шаге 4 вам придется одновременно нажать и удерживать их.
3. Включите компьютер.
4. Нажмите и удерживайте клавиши Command-Option-P-R до появления серого экрана загрузки.
5. Удерживайте клавиши до тех пор, пока компьютер не перезагрузится и вы не услышите сигнал загрузки во второй раз.
6. Отпустите клавиши.

Resetting NVRAM / PRAM
1. Shut down your Mac.
2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Turn on the computer.
4. Press and hold the Command-Option-P-R keys before the gray screen appears.
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6. Release the keys.

After resetting NVRAM or PRAM, you may need to reconfigure your settings for speaker volume, screen resolution, startup disk selection, and time zone information. If issues persist, your Mac's logic board battery (not a portable Mac's rechargeable battery) may need to be replaced. The logic board battery helps retain NVRAM/PRAM settings when your computer is shut down. You can take your Mac to a Mac Genius or Apple Authorized Service Provider to replace the battery on the logic board.

Resetting NVRAM in Open Firmware

If your computer is Open Firmware-based and you are unable to reset NVRAM as described above, you may alternatively reset the NVRAM and Open Firmware settings using the steps in the Solution section of Message “To continue booting, type 'mac-boot' and press return”.

In some cases, an Open Firmware-based computer may not respond to the keyboard commands noted above, and may not allow starting up into Open Firmware by pressing and holding the Command, Option, O, and F keys during startup. If you are unable to get to an Open Firmware prompt (and your Mac supports doing so), try holding the power button held down continuously during start up.