[Q] Bricked N7 2013 LTE

Hi everybody,
I own a N7 2013 LTE (deb) with Android 5.1.1 installed (build: LMY48P). This morning I've tried to turn on my device and it remains stuck on Google logo. :(

The device correctly goes into Fastboot mode but from here I cant do anything:
Start: see the Google logo and stuck
Restart bootloader: correctly reopen the bootloader
Recovery mode: see the Google logo and stuck
Power off: correctly power off

These are the informations showed in the Fastboot screen:
FASTBOOT MODE
Product Name: deb
Variant: deb 32G
HW version: rev_e
BOOTLOADER VERSION: FLO-004.05
BASEBAND VERSION: DEB-Z00_2.44.0_0213
CARRIER INFO: None
SIGNING: yes
SECURE BOOT: enabled
LOCK STATE: locked

I've downloaded Nexus Root Toolkit v2.05 by WugFresh and the device is correctly seen from my windows pc and from NRT (I've succesfully installed USB drivers).
From NRT I've tried to "Flash Stock + Unroot" but I cant flash because the bootloader is locked; so I've tried to unlock the bootloader from NRT, the N7 correctly show the "Unlock bootloader?" screen, I move to "YES" with the volume keys but when I push the power button to confirm, nothing happens and the tablet continues to show that screen (I've waited about 30mins and nothing happens).

I dont care about user data and my photos and videos; I'd like to have my tablet working.

Some questions:
1) is there a way to launch a stock recovery or a TWRP recovery from NRT so I can wipe all data and have my tablet back working?
2) is there a way to see from NRT le log? I'd like to see some more specific error details when I try to unlock bootloader and it fails.
3) do you have some advices? thanks in advance

Thanks guys