previous morning, i wake up 6 am (which i have experimented 4 days to found my excellent REM lucid dream phase) and doing WILD technique. At first, im doin well and everything go smoothly using the visualizing "I am dreaming" words behind my eyelids and suddenly, it seems like i entered lucid dream. when i tried things out, everything suddenly go pitch black and im feeling mad vibration, then i woke up(not FA or anything).

my question, did i do things wrong?
what happen?
is the scene before the mad vibration just a active imagination?
when im lucid, what are the first thing i must do?