Make sure you are using newest firmware. Download the most recent plug-in bundle pack from this website (icecrypt/plugins/plugin bundle for s3500) and put on usb stick. Go to box and 'settings' then 'system recovery'. Choose 'format user data' and wait for box to restart. When restarted insert USB stick into box and go to plugin press 'red' to download and wait for box to restart. Go to 'plug-in' and the xcamconfigure to enter line.
If this fails the other way to configure is to download the most recent individual xcam plugin and from pc/laptop edit cardconfig.conf by going to folder called etc and using notepad (.conf to .txt and back again) and enter line at the bottom of the file and save and 'format user data' put plug-in to USB then box then download as before. The icecrypt S3500 has a memory and unless the xcamconfig in someway is altered it will use the old line.