So recently, my old Logitech G710+ starting weirding out on me – the WASD keys don’t light up, intermittently. It’s not a switch problem, it’s an LED problem. Other than that, the keyboard still works.

That’s the downside to backlit keyboards – once the lights don’t work, you kinda don’t want to use it anymore, EVEN IF the keyboard itself works FINE (as in, you press a key, the correct letter comes up).