I need to replace the headlamp bulb on 2012 Vespa LXV 150. I have searched around and cannot find instructions for LXV headlight. Does the plastic cover twist off?

http://modernvespa.com/forum/topic13379
http://modernvespa.com/forum/topic101574
http://modernvespa.com/forum/topic16615
https://www.youtube.com/watch?v=TgFp0jszqTA
https://www.youtube.com/watch?v=doqINK4bgn8
manual below
https://www.manualslib.com/manual/1290767/Vespa-Lx-150-4t-Usa.html

It may be a plug for recharging the battery with a trickle charger.

check:
1) is the battery good?
2) did you use the brown master-key?
3) is gasoline full?
4) is the kill-switch off? (if there is one)

The 2003 Outlander utilizes replaceable (9007) headlight bulbs. If you're looking to replace the bulb(s);
1. Raise the hood.
2. Remove the plastic cover at the rear of the headlamp assembly by rotating it counterclockwise, and pulling it off. This will allow access to the headlight bulb.
3. Twist the bulb socket counterclockwise in order to remove it from the headlamp assembly. Pull the old bulb out of the socket, and use a clean cloth to install the replacement bulb. Do not touch the glass of the new bulb.
4. Place the socket back into the assembly, and twist it clockwise. Reattach the plastic cover, and close the hood.
Are you needing DIY instructions for replacing the entire headlamp assembly? Left (driver) or Right (passenger)?

It will take two people if yours are anything like mine, If you look at the headlamp you will see a plastic piece, this locks the headlamp in the position, You need one person to push in on the headlight and one to pull out the plastic stop, then you can change out the headlamp. If you have the part you can also take it to a dealer and they will charge you around 10 bucks to do it, almost worth the hassle!