Via Cordcutters News, we learn that Roku, Inc has been replacing defective streaming hardware:
Thank you for your recent purchase of a Roku 4, the newest addition to our line of streaming players. We are getting in touch after discovering a manufacturing glitch with a small number of Roku 4 players. We identified your Roku 4 player as potentially among this group, and as a result would like to replace it to avoid any potential issues that would impact your use and enjoyment.
While Roku hasn’t indicated what exactly the “glitch” is, and Cordcutter News hasn’t speculated, I assume it’s heat-related given multiple reports of units with noisy fans (and at least one that melted). As the recall has been going on for several months, with new outreach this week, I suspect Roku was unable or unwilling to pull the impacted batch from shelves — so, as boxes come online, the company contacts registered owners to arrange swap. By comparison, Amazon’s 4k Fire TV must run cooler, as it was engineered to dissipate heat without requiring a fan.