You cannot review a video by using the rev button.
You can only review a still picture by using the rev button.
Since you removed the battery, make sure you have inserted it correctly.
Newer Panasonic cameras can only work with Panasonic batteries.
Try removing the memory card and see if it will turn-on without the card.
I was using the camera. To see the preview I pressed "rev" button erroneously and camera switched off instantly. I tried to switch it back on but it wont. Thinking that the battery might be weak, I cleaned and recharged the battery and reinserted it. the camera still wont turn on. What should I do? I need your help please.