If you already had patented your idea and demonstrated it to potential investors, without a non-disclosure agreement, then your idea no longer qualifies for Edison Nation to handle it. However, if you do have a non-disclosure agreement, then they may still legally take over continuing the process for you. It’ll be their decision after reviewing your case.
On the other hand, if you came up with the idea, but you discovered that someone else already had a patent on it, and already had a prototype and showed it to potential investors, then it might be too late for you.
The only exception might be if your idea has additional features that serve the potential user, and those features are clearly missing in the other person’s patent description. You need to scrutinize their patent. Having it reviewed by a patent attorney would be crucial in that case.
If their patent has been written well, by a good patent attorney, and includes claims for every possible configuration of the idea, with claims for all possible features and modifications, then, in that case, it’s best to move on and try to work on another idea.