Solved
Roku Express tries to update then restarts
I’m having the same issue but my USB is plugged into the wall not the tv.
many suggestions?
MissHall, it wouldn't hurt to try another USB power adapter/charger from a phone or tablet and/or another USB cable. Look at the fine print on the adapter for something like, "Output: 5V 1A (or 1000mA)". Anything greater than 1A/1000mA is all right as well, but less is not. After that, about all you're left with is a factory reset, but note that if you've been using the app as a remote you must have a functioning physical remote to set up a device after a factory reset.
How to system restart or factory reset your Roku streaming device | Official Roku Support
