Thanks everyone for the help, I was a little nervous, but disconnecting the battery cable and reconnecting it DID allow me to hold down the power button and restart the device. With the original SD card in place, things were back to normal.
I then went about the *long* method of cloning my SD card.
I'm posting this for future (mac) readers, or myself, if I ever cross this way again.
1) Open the back of the Clara, starting at the bottom of the cover near the power button/charge port, pry it off from the frame.
2) Remove the SD card, and put it in a SD card reader in your mac.
3) open a terminal, type '
diskutil list' and find what disk your SD card is.
4) type '
sudo dd if=/dev/disk# of=~/Downloads/Kobo/Clara.dmg bs=4096'
where disk# is the number you found in step 3, if is the input file and of is the output file. This step takes a lot of waiting time.
5) eject your SD card (KOBOeReader) and swap in your blank SD card.
6) verify the location of the SD card again, type '
diskutil list', should be same as step 3.
7) verify the blank SD card is erased, type '
sudo diskutil erasevolume FAT32 UNTITLED /dev/disk#'
8) unmount the SD card, type '
diskutil unmountDisk /dev/disk#'
9) copy the backed up partition table over to the new SD card, type '
sudo dd if=~/Downloads/Kobo/Clara.dmg of=/dev/rdisk# bs=5m'
again, this will take some time. You can press CTRL + T to check the status.
At this point I tested the microSD card in the Kobo and it does work, but it only detects an 8GB card. To get the full capacity of the new card you need to resize the partition to take up the rest of the volume.
But, Macs can't resize Fat32 partitions on the fly with the built-in diskutil (or disk utility front end). So, I'm currently looking into ways. However, I don't really want to have to install a virtual machine of windows or create a live USB stick to run Linux so I can install gparted... So I'm kind of stuck.
I did try
some software* but although it DID resize the FAT32 partition, the KOBO would not boot up. I tried it 2 more times but every time I resized the partition the Kobo would fail to boot. *sigh*...
*Not an endorsement.