This problem has just started happening with my unit as well. Purchased in 2017, has worked fine all that time. Not plugged into TV, using wall adapter that was shipped with the unit. Testing that shows sufficient stable power output, so the issue must be software related. Seems to happen most frequently when changing a channel. Affected unit is Roku Express 3700X ( S/N: YU00RV627141, Device ID: 7G26DR627141, Software 9.4.0 Build 4200-28) We also have a Roku Express+ 3910RW that does not appear to be affected (also plugged into wall adapter, Software 9.4.0 Build 4211-51) A power reset will clear the error, which is random, and the unit will work again for an indefinite time. Have not tried a factory reset/rebuild, since if it is the latest software, the problem will just recur.
Given that Roku does not appear to have any live support for these products (the support site indicates no chat support available, and there is no way to actually contact a real person at Roku) is the only solution to junk it?
Very frustrating, as is the other planned obsolescence of these units - I've had two others prior to the Express units that I had to replace because they were no longer supported, even though there was no hardware problem with them. It is unfortunate, since they do work well, and are easy for everyone in the house to navigate.