Why wont my Nexus 7 flash properly?

[Monobrows78]

After my Nexus 7 (2013 Wi-Fi) upgraded to 5.0.2, it came under siege from bugs and glitches beyond count. The launcher would freeze, apps would close themselves without warning and it all piled on until I became so enraged with it that I attempted to reboot it back into Kitkat 4.4.4. For reasons unknown, disaster has happened and now it is both without any data beyond the bootloader and refuses to accept any attempt to flash a 4.4.4 onto it. Does anyone have any idea of how to fix this?

Update: When the screen loads it displays the android guy on his back with open button chest and says

Fastboot Mode
PRODUCT NAME - grouper
VARIANT - grouper
HW VERSION - ER3
BOOTLOADER VERSION - 4.23
BASEBAND VERSION - N/A
SERIAL NUMBER - 015d3b6642181006
SIGNING - not defined yet
LOCK STATE - UNLOCKED

Photos of input/output of command windows are attached.

 

[Paul627g]

Try using Wugs Tool Kit. Usually this is a great go to app to help get things going again.

Nexus Root Toolkit v2.0.4 | WugFresh

 

[Monobrows78]

It appears that something was simply wrong with the download the first time around. I compared the two files and almost half a megabyte of data was missing. Redownloaded, used Wugs, thanks for the tip!