One thing Roku support is not mentioning for a possible solution is to leave the batteries out for 8+ hours which allows the remote to cold-boot after the software update. Sometimes a device needs to cold-boot in order to complete a software update and with the simple machinery of a remote, the only way to do this is to completely power down the circuitry by removing the batteries for a long period of time. This is akin to the same solution provided when you unplug your router and modem in order to reset it, although you only need to disengage power for 30+ seconds!
If not, the problem is likely with the remote itself: possibly a large capacitor that basically allows the remote to work as it should without a constant use of battery power. If the capacitor fails, the flood gates are open to constantly power the circuity whether it is called for or not; it would be as if every button on the remote is being pressed simultaneously and held down indefinitely.
Another, however unlikely, problem is a "sticky" key, that could be engaged enough to signal a constant command but still allow the key to carry out its function: when pressed again the key would disengage only to re-engage; or, an irrelevant key that just stays engaged. I know on the Roku Ultra base unit if you see a constant light flashing very quickly, that means a command is constantly being sent; and, will only stop sending a signal when another key is pressed. But I believe, even if you don't see a constant flash on the base unit, a key could still be causing a constant drain on the batteries. Very unlikely, but still a possibility, since you can hold down a button and successfully carry out another command using another button.
