Try Chromecast. (The device is about $25. The software is free - Chromecast.) About the only problem is seeing a portrait hone on a TV screen (which is landscape by default) - only the middle third of the screen is being used. (You can't stretch the video to fill the screen - everything would be distorted. But with the phone in landscape position, everything looks fine on the TV.)
The TV has a USB port, so you can power the Chromecast through that, or use the included AC adapter. The Chromecast itself plugs into one of the HDMI ports.