If you happen to have a Steam Link that starts up to the initial boot screen and then turns off, maybe after trying to update to the latest firmware version, here is something you can try to hopefully get your Link working again.

This will only work if your Link is able to at least turn on and recognize USB drives.

  1. Open http://media.steampowered.com/steamlink/06_2015/public_builds.txt and note the highest number at the bottom (even though any version in this list is supposed to work for our use case)
  2. Download the update package from http://media.steampowered.com/steamlink/06_2015/SystemUpdate_full_xxx.zip while replacing xxx by the number you just noted
  3. Get an USB flash drive and format it as FAT32
  4. Rename the downloaded package to SystemUpdate.zip and put it into a folder called steamlink in the root of the USB drive
  5. Also create a text file called update_branch.txt containing the single word public and put it into a new folder at steamlink/config/system
  6. Make sure the Link is not powered, plug in the USB drive and then connect the power
  7. The Link will start its update process and will then boot normally

In my case, after doing this process, the Link reverted to one of the early versions (around 200 if I remember correctly) so it needed another pair of reboots to finally update to the latest version. YMMV