Ok, well blinking and flickering are two completely different problems so it pays to be precise in order to diagnose the problem. Could you report exactly what it is doing. "blinking out of control" could mean it switches to tactical strobe or it blinks twice and drops one level depending on the person reporting.
Did you switch battery types? aka primary to rechargeable, and did you wait a couple minutes between the switch.
It sounds like a battery detect problem or a contact problem. Before sending it back to RA, I would try a brand new 2019 dtd
USA made CR123, and also clean the contacts.
I apologize that this sounds like I'm the Microsoft help desk asking if the computer is plugged in and having you tried rebooting, but ya got to cover the basics first