Bought a new remote for my roku express off Amazon so I could have one with the power button and volume controls. There is no pairing button under the battery cap. I’ve reset the roku, I’ve used brand new batteries. Nothing works. And of course you can’t call anyone at Roku. Roku your support is god awful and I doubt I’ll ever purchase your product again.
The only roku remotes with tv power and volume without a pairing key are Roku tv IR remotes, which is useless on a stand alone roku like the express. There is the Onn IR roku smart soundbar with tv power and volume keys but they're not sold separately and you can't find one on ebay. You bought the wrong remote, sorry.
Only wifi remotes have tv controls, and if your express is 3700 it won't work with wifi remote. You want remote that controls your roku and tv, get a cheap universal remote from target or dollar store.