You state that you recently replaced the controller and LCD. WHY? Did anything unusual, anything at all, happen around this time, and exactly WHEN was "recently" in relation to when this problem occurred?
Battery sag past LVC is what you are describing is happening. This can happen because the entire battery is low, this can happen because a single cell is too low, OR it can happen with a controller, like a recently replaced one, has an LVC which is too high.
Unless it shows on the LCD screen, I do not know of a way to check most controllers for what their LVC actually is.
Do you still have the original controller? Or can you borrow one?