What Am I?

Hey everyone,
Sorry I haven't posted the usual Guess It poems for a bit, its been a crazy week!! But good news, I'm back on track and here's todays!!

You push my buttons.
Its my job,
Though I never find it annoying.
I know just how to turn it on.
I love to go up and down,
Though I can be a mute at times.
It may seem I'm always getting lost,
But I just like to sit,
In the last place you look.
I can be fancy,
Or plain as can be.
Either way,
I live to serve.
My best friends,
Give me a charge!
I only have one pet peeve.
When I fall asleep,
You think you need to bang me
On things,
To wake me up.
You hold the power,
There in your hands.