Echostar have posted this on a few forums....
We have today released a new software version 123R for the HDS-600RS. This update will ensure that you can successfully scan for new services when Freesat adds more channels to provide increased coverage during the Summer of Sport.
Your box should automatically receive the download over-the-air, however, if you do not get the download then you can receive the update by manual download, Internet download or by pulling an over-the-air download.
We are aware that a small number of new customers may experience problems when scanning for services resulting in the box locking-up. In order to correct the issue and enjoy the additional services you will need to bypass the set-up wizard on the box to download the new software.
To ensure that you continue to enjoy optimal product performance, we suggest that you update your box as soon as possible. After the download appears to have been completed, please check to see if the latest version (123R) is registered in the menus (how to check software version). If your first attempt was not successful, please try again at a later time of the day - due to network loading at peak times, updating over the Internet may occasionally take longer than is expected.
EchoStar Support Team
You can download this over satellite but it's usually more efficient via the internet. Hot the Sling 'U' button > Settings > Techical info > Check for updates and then when prompted allow the 123R download. You can even do this remotely (as I did) as it reboots the HDS and it automatically goes back online after about 10-15 minutes. Apparently it's going to make updating the box for new channels better- whatever that means!