Wow, 3400. Hate to break it to you, but that model is no longer supported. That is the MHL version of the Stick, first released in Oct 2012. It's tough to find MHL compliant devices any longer, and it's most likely stuck in the loop because of its legacy status. Support was discontinued for it almost a year ago, and you'll find that many of the newest channels won't even install on it.
One trick that has worked for others that are stuck in an update loop is to use an alternate Internet source, such as a phone hotspot. It makes no sense, but it has worked for many people. However, they weren't attempting it with a legacy player.
If you decide to just replace it (and I think you'll be happy if you do), remember you can't plug a standard HDMI device into an MHL jack. They are physically identical, and it will plug in, but it won't work. If your TV also has a standard HDMI jack, you can use that one instead.
Dan
Roku Stick (3600), Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
