This is what happened:
I tried to enter any sudo command (e.g. sudo visudo) and entered Pi's default password(raspberry if you don't know) and this is what it came up with:
pi@(none) ~ $ sudo apt-get update sudo: unable to resolve host (none) [sudo] password for pi: Pi is not in the sudoers file. This incident will be reported.
pifrom/etc/sudoersto your question? The entry should look likepi ALL=(ALL) NOPASSWD:ALL. – ott-- Jul 24 '16 at 16:00unable to resolve host (none)... – KennetRunner Jul 27 '16 at 16:41