Have you checked the batteries? If they are Li-Ions, and you have the charger from US, you might want to stick them in there to make sure they don't need charged. If they are just the normal AAAs, then you might want to replace them. I don't know enough about electronics to tell you if something else might be wrong, but the batteries are a good place to start.
Also, your English is just fine. I would never have known if you hadn't said anything.
It's an Obsidian Lite, so it cannot have the Li-Ion setup.
And yes, fresh batteries tend to solve a lot of problems. Generally speaking, any time any of the soundboards start saying "Obsidian" and shutting off, it's time to recharge/replace the batteries.
And I'll bet your blade's a little bit brighter now too. Usually with the AAA battery setup, the blade will begin dimming when the batteries start getting low. As opposed to the Li-Ion setup where the blade brightness remains the same, right up till the batteries need to be recharged and the saber just shuts off.