The battery has finally degraded to the point that it won't hold or pass voltage, so yes it needs to be replaced. Luckily, with a few skills, such as disassembly and soldering, you can remove and reinstall a new, rechargeable battery that should get the razor working like a champ.
Electric Shaver Service stocks most rechargeable replacement batteries for almost all electric shavers made.
Here's a link to the battery page, just find your model and you're ready to go. If you want, you can call and confirm which is the correct replacement battery for your specific model shaver too.
http://www.electricshaverstore.com/search.asp?p=1&w=%5F&c=battery&t=s
Hope you find this Very Helpful and best regards!