Can I boot my Macbook via my SD card?

It should workthe same way. Use another mac to make a bootable SD card... Need isntructions on this?

You can boot from a SD card without any problem. Press Option key while your Mac is starting and select the SD card. As you are seeing the flashing folder, open Disk Utility, select Macintosh HD in the sidebar and verify the disk. If it's damaged, repair it. If it doesn't work, the hard disk is damaged and you have to take the computer to an Apple Store.

If it doesn't find any problem, reinstall OS X. The installation is the same as you do from a USB drive, DVD or Recovery HD

You cannot start a .dmg as a boot disk. You have to mount it to the SD card. For this to happen, follow these steps, if you have access to a computer with Disk Utility.

1. Boot a computer into normal opperating mode.
2. Open disk utility.
3. Move the dmg to the desktop
4. Erase and format the SD card to MAC OS Extended(journaled)
5. Open the partition tab.
6. Make a new partition by selecting "1 Partitions"
7. select "Options" at the bottom of the list of partitions
8. make sure "GUID Partition Table" is selected
9. Press "Apply"
10. Open the .dmg file
11. In Disk utility, select the newly created partition on the SD card
12. Open the "Restore" tab
13. In the top box, you should see the partition itself. Drag "InstallESD" disk into the bottom box.
14. Press restore.
15. Once the restore finnishes, you should now be able to boot from it
16. Plug the SD card into the SD card slot
17. Reboot the faulty mac.
18. Press and hold the option key after you press the power button.
19. Hold the option key untill you see the drive select menu
20. Select the name of the SD card (probably InstallESD now)
21. The rest of the process should guide you.

Cheers!

Hi- what and where is the dmg file?

<< 10. open the .dmg file >>

thanks!