Since a longer time, most of our models feature a transportation lock to prevent your light from accidentially switching on in your backpack, suitcase etc.
So if your light only flashes / flickers, when you try to turn it on, you have probably only unknowingly activated the transportation lock. That is is what the flashing / flickering wants to signlise.
To activate or deactivate this function, simply press and hold the switch for several seconds.
Depending on the model, this can be between 5 and 19 seconds. The time to deactivate is often shorter than to activate, sometimes it is the same.
In our Quick User Guides (QUG), we always show this function with the lock symbols, such as here for models MH10 / H8R: