Nexus 7 Bricked after fastboot error - bootloader works

[dupczysko]

I was trying to install android 6 over the fastboot. When system.img was writing to device, transfer was stop by error. Now device is not visible at ADB DEVICES. When i enter device manager it show Android Bootloader Device. I was trying universal driver (Google nexus 7 universal bootloader) but it still the same. I was trying on other computer also with linux but with the same result. When i power on nexus with volume down bootloader shows up with this log:

FASTBOOT MODE
PRODUCT NAME - GROUPER
VARIANT - GROUPER
HW VERSION - ER3
BOOTLOADER VERSION - 4.23
BASEBAND VERSION - N/A
SERIAL NUMBER - 105D...
SINGNING - NOT DEFINED YET
LOCK STATE - UNLOCKED

When i try to start or enter recovery mode, i get: booting failed.

Is there any hope yet?