Optima XM All lights fixed red except day which is green?

We have had an Optima XM alarm fitted in our house for 16 years now. It has never given us 1 day of trouble since installation.

Yesterday however I went to set the alarm and noticed that all LED lights on the front panel were fixed red. The only exception is the day light which is fixed green.

Can someone tell me what this means and how it can be fixed?

Thanks