I'm unable to access my device, because it asks me to type in a password to decrypt the internal storage. I did not, in fact, place any password here, so I don't know how I got here. I've been trying to flash the device with another firmware for this reason — including CyanogenMod — but it wouldn't let me because apparently I'm not in debug mode. I can't enable debug since I can't seem to be able to boot up normally.
How do I enable debug mode without having to boot my phone, perhaps via Fastboot or Flashtool?