[RECOVERY] [OFFICIAL] TWRP for Shield Tablet

ok let’s see if I can explain my issue in another way…

some time ago I had android 5.2 with TWRP and root permissions
now I’m on Android 7 and I’m not able to install TWRP and root permissions anymore

if I go in fastboot in my nvidia shield tablet K1 I have the first picture .
if from fastboot I go in recovery mode I have the second picture. the green robot.
if from the green robot I press volume up and power button I have the third image Android Recovey

does the green robot means TWRP is missed?

now if I try to flash twrp.img (4th picture) it says waiting for device and the tablet reboots in Android OS but TWRP is always missed

I’m sure if you can send me an old TWRP version in zip format I can solve or if you are able to convert TWRP.img into TWRP.zip

what do you suggest?

Can I at least have root permissions what file must I to install? can you provide me the correct link please?