Need help recovering from bad flash

I was attempting to change my Galaxy Nexus from Cyanogenmod 10.2.1 to cm 11 (current stable release). So, I did the following:

1. Created a Nandroid backup, saved it to my laptop, and deleted it from my phone as after creating the backup I had almost no free space. Before deleting it, I did test it and confirm that it worked.


2. Downloaded the CM ROM and gapps from the CM website


3. Verified their hashes.


4. Copied them to /sdcard. I didn't think to verify their hashes again. This may well have been a mistake.


5. Used TWRP v2.6.3.0 to wipe the phone and attempt to install CM. A message appears: "Failed." Here's a sample output (note that the output falls off the right-hand edge of the screen and there seems to be no way to scroll it to make it readable):
   
   
   

   Code:

   
   

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   Updating partition details...
Installing '/sdcard/cm-11-20150626-SNAPSHOT-XNG3
Checking for MD5 file...
Skipping MD5 check: no MD5 file found.
set_metadata_recursive: some changes failed
E:Error executing updater binary in zip '/sdcard
Updating partition details...

   ---

   
   

At this point, the phone won't boot. It goes directly to recovery.

To recover, I thought I'd just copy over my Nandroid backup. But, I can't use adb in recovery. I tried to use fastboot to flash my nandroid backup, but the format seems to be different, and I wound up with a phone that, when attempting normal boot, gets stuck on the Google logo until I remove the battery. I do have access to recovery still.

How can I get something bootable on my phone? I just want to restore my Nandroid backup. (And maybe see if I can figure out why CM-11 didn't work.) I can't find any way to copy arbitrary files to my phone.