Linksys E900 - DD-WRT Wiki
https://wiki.dd-wrt.com/wiki/index.php/Linksys_E900Download the stock firmware image from the manufacturer's website or here, reset the router back to defaults using a 30-30-30 hard reset, then flash the stock image from within the dd-wrt webgui. After 5 minutes it should finish, you will then need to do another 30-30-30 reset and then access the stock webgui @ 192.168.1.1