One of my IC1004-WH Legrand ON-Q Inquire 1000 intercoms isn't working, is it possible a POE injector would help?

One of my IC1004-WH Legrand ON-Q Inquire 1000 intercoms isn’t working, is it possible a POE injector would help? It’s a pretty long run, although other longer ones are working. It has worked somewhat in the past but gave a bad hum. Now it doesn’t work at all. I have two different ones I’ve tried, with the same result. Circuit checker says I’ve got continuity all the way through but I know it might not be enough to carry a power signal.