C43865093143 is the only number on device. No idea what type. Just a little rectangle box. Says roku. Roku remote would not work when we plugged it into tv. So I reset the box manually. It went to language screen. Let's get started so after that came up I hit the sync in battery compartment. Light blinks green but it never syncs. Cannot get set started without remote
Okay, we've ruled out a Stick.
And you're saying the words "Model No." don't appear on the box? Not on the bottom of the box, for instance? Because Roku usually puts the model number on the device itself.
Apart from that, the fact that you're seeing a green light indicates the remote's batteries are working. New batteries might still help.
Since it's not a Stick, an IR remote will work on that box. If you have a universal remote lying around anywhere, or want to spend $5 or so on a cheap universal remote from Family Dollar, Walmart, or some other place (as long as it's compatible with Roku), you could use it to set it up.
I'm curious. How did you get the device? I don't need details, of course, but "found in a drawer", "bought from a store", or some history on the device might help.
If it's a current device, and you're in the U.S. -- you didn't put your location on your profile -- then it's either a Roku Express, Express+, Premiere, Premiere+, or Ultra. If it's an older device, it could be one of any number of models. So, history might help.