Lionel has had an epidemic of faulty fan motors to this day. I've heard video of recent new releases with very noisy fan motors.
When you say "powering manually" How are you powering it? Folks have gotten fan motors to work via 9v batteries that didn't work with the 5v from the board and still needed replacement.
The first thing you could try a is a drop of light oil on the fan motor output shafts bushing . You have to remove the impeller with needle nose to get at the bushing.
If that doesn't work its likely new motor will be in order.
The on board diagnostics works via voltage draw . If it senses excessive draw it shuts down power to the fan and the cab light blinks. You can reset the code via the reset on the remote up to 3 times. After three times the fan motor shuts down completely . Removing power from the Loco and repowering gives you another 3 resets and so on.
