This is the Breitling Aerospace that I had.
As you can see, the date display is flashing. It is indicating that the battery needs to be replaced. The question is, do I do it myself or advise the owner to send it to Breitling to get a full service. He wants me to just change the battery, but I think it should be sent to Breitling.
I think I will tell the owner to send the watch to Breitling.