By Graham K. Rogers

I cannot really explain what I did, but I tried an experiment on the MacBook Pro earlier today with the display and it failed. While there are some things that can be done with an external display, the same may not be true with a 3-year old MacBook Pro. I tried to make a change: my mistake. The screen went black.

A restart did me no good and on online search for a fix, left me no better off. With the specific System Preference unable to load and no trace of a .plist file that I would need to effect a repair, I was faced with a situation I could not fix. I decided to shortcut everything and use a Time Machine backup.

I had a backup disk at home that I had used early in the morning; and there was another in the office that had completed a backup just after I arrived - and before I started playing about - but there was another problem: the Firmware Password.

I lock up the Mac using the Firmware Password Assistant utility which is now on the Rescue partition. This is opened by starting the Mac with the Command + R keys, but that then needs the Firmware Password. For added security, I write this on paper and lock it away at home, then forget it. It doesn't help that one of the characters used is wrong (I forgot the Shift key), but when I do remember the error, I convince myself that this is just added security.

At home I made sure the Mac was charged and entered the Rescue Partition, which mercifully was not affected by the damage I had wrought earlier. I ran Disk Utility, but that found nothing, then selected the top item in the list of options: Restore from a Time Machine backup. There were a couple of warnings about what might happen, but I started the process and it began to search for a hard disk with a Time Machine backup.

This is different from installing a Time Machine backup onto a new computer setup when the user is asked to connect a disk at an appropriate time. I had to press the Back button and connect the Thunderbolt cable. It found the disk. I highlighted it (the only one shown) and I was offered a list backups available. I chose the most recent (0845 19 Aug), pressed Go and when a time of over 3 hours was indicated, went off to do other things.

The actual time for the process was about an hour. I noticed that the lights on the disk had stopped flashing, so checked. The main login screen was available with all the accounts. When I entered my User account, there was a process of checking as software started and Little Snitch wanted me to be sure about every outgoing connection.

Aperture needed a repair: I had shut down when this was running. Mail needed to import mailboxes; and Dropbox wanted me to enter a password. The rest was close to how it had been when I started work in the office, apart from two text files. I knew they had not been backed up, but in the twilight state I had in the office, I copied the contents into email messages and later copied the text into TextWrangler.

With everything ready, I ran Time Machine, but that revealed another problem. Both of the disks I had (I brought the office backup home too), showed Preparing Backup in the Time Machine preferences, but never began backing up. In the back of my mind, I was aware that this had been covered before and a Google search found me links to older articles on this by Paul Horowitz on OS X Daily, and the Cocktail Blog.

The solution was to stop the backup and navigate to the folder name Backups.backupdb and in there open the folder for the Mac I had the problem with (more than one device can be backed up onto a disk). In that folder, near the bottom was a file marked with the current days date and the words "inProgress". I trashed that, unmounted the disk and repeated the process for the other disk.

We are now up and running again.

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs. He is now continuing that in the Bangkok Post supplement, Life. He can be followed on Twitter (@extensions_th)