JFJ_595 wrote:
the start-up music still plays.
The POST for the hardware checks out then.
JFJ_595 wrote:
I turn on my computer and all i get is a blank white/grey screen. No logo, no loading symbol, just a blank screen;
Command+R does nothing,
Holding Shift does nothing
Press and hold the power button down to turn of the machine.
Press and hold the Command Option R keys on the built in keyboard and press the power button, you have to be near your high speed Internet connection.
If you get something like "Install OS X" do that, it will overwrite your old copy with a new one and not touch your files or most programs.
If you can't install OS X, head to Disk Utility and First Aid > Repair Disk and Permissions and try reisntalling OS X again. (do not erase the drive as this will wipe your data off, unless your sure)
If you still get the white/gray screen with nothing while holding the Command Option R keys at boot time, I suspect your EFI firmware has been borked somehow and it's not loading to respond to the at boot key commands.
We are able to reinstall the EFI firmware ourselves, but the current method requires a machine with a internal optical drive. This problem occurs so rarely that it's not been used much and certainly unknown how well it works off a USB thumb drive, which is what I suspect the Apple Store/Repair will do.
Since your under warranty, I would have Apple replace the EFI firmware and check the machine out for hardware issues as well.
Buy AppleCare and a external drive for TimeMachine backups.