Word of warning. I've got the same problem with my Edge 820 which i bought when they first came out in July 2016. When i spoke to Garmin UK, they told me basically go do one.
In Denmark we have 2 year warranty. If we have a faulty item fixed or replace, the warranty (on the fixed issue) is another new 2 years. I don't about other countries... But in my case I will send it back every time the halo comes back.