AL19
If you are seeing the dancing Roku letters two things come to mind (Power Savings Feature or Power Supply Issue)
1. Disable the Power Savings Feature if available on your device.
Settings/System/Power/Auto-Power Savings/20-min [Disable]
2. If you are currently powering your Roku device via the USB power port of your TV, try using the supplied power adapter and plug directly into wall outlet. If currently using the power adapter, try replacing the power adapter will a cell phone charging adapter (5volt, 1amp).
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Feel free to post an update and include Roku model number and OS build number. (Settings/System/About)