Garmin Edge battery replacement

I have a semi-elderly Edge 820 which has been pretty good, but in the cold weather the battery now only seems to last a couple of hours.

Has anyone tried replacing the internal battery on a Garmin? Having done this on a few other gadgets, I suspect it’ll be fine, but anything involving adhesive is a real pain.

I once did it on an Edge 705. Simple to do and completely restored the original battery life.