I have a Nexus 7 3g, two days ago I rooted it so as to enable the tethering option. The rooting procedure I followed went well.
However, there as been some problem while enabling the tethering because at the boot the tablet was blocked while loading the OS.
So I decided to reinstall it but I had some problem and now the situation is that when I try to access to the recovery mode, I get the red triangle. I push power and bottom up, and I wiped all the data as suggested, typed "adb sideload android_4.3_stock_tilapia.zip", and got the error E: footer is wrong. E: signature verification failed.
I saw in the forum that I cannot use adb sideload to install a new OS but only for updates....
My question is: How can I use fastboot If when I type "fastboot devices" I have no device listed?
I thank you very much in advance for your help.