I had the same problem with a Motorola W375 on sister network Net10. As "defective" according to Tracfone means no ability to make voice calls only, you are probably better off just buying another Tracfone. If you attempt to have them rectify it, they will just give you the runaround of try this and that until the warranty expires. If you want to try anyway, Executive Resolutions is open between the hours of 8 and 5 EST at 1-800-876-5753. I also have a contact (Elston Lombillo) within the company that handles the tough problems as well as he is allowed to by Carlos Slim (the owner), I can PM that e-mail to you if needed. Elston was able to rectify a problem for me recently, but it involved a messed-up minutes transfer to a new phone. Unfortunately, as a phone is required to not be able to make a voice call in order to be deemed defective under warranty, I think you are out of luck -- even Elston is limited by company policy.
To web browse with the 420G, press the globe button on the keypad. It is the key above SEND.
If you are getting "Connection Failed", it is possible that the carrier has not yet activated Mobile Web for the phone. After a new phone is activated, TracFone's web site states to wait one hour before accessing Mobile Web.
If you continue to get "Connection Failed" after a period of time, then you should call TracFone to get it rectified.
I noticed earlier today that the TracFone default home page that appears, had some server problems and displayed an "HTTP Error 500". Going to the Navigation selection on the menu then selecting Reload, will reload the page.
To save any favorites, you would save them as Bookmarks, once you are on that particular page while web browsing. To look at the Browser menu without launching the browser itself, press the Menu key then 5 (or navigate to the center icon).