fastboot flash recovery img never completes My Nexus 10 stopped booting. It shows an open padlock on startup and the Google text in the middle. So I figured my son unlocked the bootloader somehow after creatively following instructions he found on youtube.
I then tried to proceed to installing a fresh rom. Saw that CM has the "Manta" roms.
I have handy the main rom: cm-13.0-20160820-SNAPSHOT-ZNH5YAO0J6-manta.zip.
I found two recovery roms: twrp-2.8.7.0-manta.img and cm-13.0-20160820-SNAPSHOT-ZNH5YAO0J6-manta-recovery.img.
I'm able to get fastboot to see my device, after doing the vol up+down / power thing. But then the command fastboot -w flash recovery cm-13.0-20160820-SNAPSHOT-ZNH5YAO0J6-manta-recovery.img never completes.

Creating filesystem with parameters:
    Size: 29783752704
    Block size: 4096
    Blocks per group: 32768
    Inodes per group: 8192
    Inode size: 256
    Journal blocks: 32768
    Label: 
    Blocks: 7271424
    Block groups: 222
    Reserved block group size: 1024
Created filesystem with 11/1818624 inodes and 158176/7271424 blocks
Creating filesystem with parameters:
    Size: 553648128
    Block size: 4096
    Blocks per group: 32768
    Inodes per group: 6768
    Inode size: 256
    Journal blocks: 2112
    Label: 
    Blocks: 135168
    Block groups: 5
    Reserved block group size: 39
Created filesystem with 11/33840 inodes and 4363/135168 blocks
sending 'recovery' (7860 KB)...
OKAY [  0.932s]
writing 'recovery'...


That never finishes. The tablet shows, aside from the laying down Android picture and the info, a blue line: "FASTBOOT STATUS - flash:recovery". It never gets past this.
I tried this with both the recovery img files I found.
Anyone have any idea why my Nexus 10 can't seem to complete this fastboot recovery installation? I'm doing this using Xubuntu 15.04 btw, and I don't have Windows handy. I seriously hope it isn't a Linux limitation thing. adb has always worked great. Fastboot sees and interacts with the device, so, that part should be good I hope.
Don't use CM recovery. Get latest TWRP here. Report back if this doesn't work either.

Also, you're supposed to get other partitions up-to-date to ensure compatibility with new ROMs. If you're not sure, flash a factory image.