My E25BT headset is dead without using it

I haven’t used my E25BT headset since 2 years. I even didn’t open the box. Yesterday when I unboxed it. It didn’t turn on. I have charged it multiple times for longer duration. While charging the charging light turns on and goes off after some time like it is fully charged but after removing from charging it has nothing, no light what so ever. Not appearing in Bluetooth menu. Is it actually dead?