after upgrading the original firmware on linksys ea4500 its almost impossible to get the original back because linksys does not provide the link to the download- anyway i stumbled on this link when searchin the web to solve my problems so I just wanted to make it easier for al you others
just copy paste to your browser
http://download.linksys.com/updates/to0037258865.pdx/FW_E4200_2.0.36.126507.SSA
/enjoy