was installing the last OS Yosemite upgrade and after hearing the start up music a folder with a question mark started blinking and nothing else happened. What's going on? How do I get back up?...
MacBook Air, iOS 8.3
Reset PRAM. http://support.apple.com/kb/PH18761
Reset SMC. http://support.apple.com/kb/HT3964
Choose the method for:
"Resetting SMC on portables with a battery you should not remove on your own".
Start up in Safe Mode. http://support.apple.com/kb/PH18760
Repair Disk. http://support.apple.com/kb/PH5836
Reset PRAM. http://support.apple.com/kb/PH18761
Reset SMC. http://support.apple.com/kb/HT3964
Choose the method for:
"Resetting SMC on portables with a battery you should not remove on your own".
Start up in Safe Mode. http://support.apple.com/kb/PH18760
Repair Disk. http://support.apple.com/kb/PH5836
Mac Air won't restart after latest OX upgrade.
