Sorry to hear about your problem.
When last did you use 4LO?
You must be standing still and in Neutral to engage.
Sometimes you have to dive forwards and backwards a bit to allow the actuators to operate into position if you have not used it in a long time.
Only once everything is switched will the light stop flashing.
Depending on your technical knowhow, I have the Nissan manual for the Transfer System.
If the problem is electrical, this would help a lot.
It could be a faulty connecter, blown fuse or stuck actuator.
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