So without the USB harddrive enclosure plugged in, the remote works as normal. When I have the harddrive plugged in, its doing this reset loop that causes things not to work right. So definitely there is some kind of interaction with the drive that is the problem.
Is there anything I can do to debug this further? I would like to have both a functional remote, and a harddrive attached to the vero 
I suspect the drive’s PSU may not be up to scratch.
This then results in increased power draw from the Vero which starves other attached peripherals.
Do you have another USB HDD (powered) you could try using?
This one is actually powered, its an enclosure/docking station, like this:
It has power to it. The strange thing is, this has worked for at least a year, and then suddenly this started happening, which is why I was sure it was the battery, but it obviously is not.
Try it on your PC to see if it works there.
Not sure what you are asking me to try. The drive enclosure with drive works on PC.
I meant to try the remote on the PC but re-read that the remote works without the drive attached so no need to test it. Then only ideas is a powered hub