I wonder when did you download the enable-adb package? Just trying to figure out why you may have gone into the boot loop after trying to install it.
To recover you probably don't need to boot from SD card. First of all you need to get into the recovery mode. While the reader is rebooting, press and hold HOME and MENU. The reader should boot into the recovery mode and stop. You may need to hold those buttons until it stops recycling.
You can then log into the USB serial terminal, and restore the ramdisk image by hand.
1) Copy the ramdisk-origi.uimg to micro-SD card
2) Put the card into the reader
3) Mount it:
mount /dev/mmcblk0p1 /mnt/sd
4) cd /mnt/sd
dd ramdisk-orig.uimg of=/dev/mmcblk2 seek=10240 count=600 bs=512