Okay if the remote works interoperably with another radio, then the remote itself is fine.
It can be tricky to see, and your camera just may not be compatible.
So that isolates this to being a fault in the main unit.
There is one step you can take here, both as a possible fix, as well as a diagnostic evaluation
1) Unplug the power cord from the wall
2) Wait at least 1 hour (60+ Minutes)
3) Press and hold the power button
4) Keep holding power button while plugging back in, and for another 60 seconds after. When plugging back in, go directly to the wall outlet, bypassing any power strips or surge protectors.
If this reset process does not work, it would unfortunately confirm an internal hardware failure. If it comes to that, I'll advise on service options for you.