The contacts to the circuit board in these fobs are horrible. I have fixed mine as well as a few others. I would not be surprised if the battery was just fine and the real problem was the broken solder joints holding the unit onto the circuit board. It's a 2 minute fix for anyone with a soldering iron.
Pioneer Avic D3-Nav System
Solo Performance Street Race exhaust & High Flo Cat
JPM interior (Shifter, wheel, console, handles & door panels)
Valentine1 flush radar display
OZ Ultraleggera Wheels
DDM Works Brakes, Backbone, intercooler