Sorry to hear you're having problems.
First I ask you the lights are new, or you already had them in your tank, or you bought them to another aquarist, or why you need to reset them?
I do not have Hydra, but I have Ai Prime. Some time ago I had to reset them due to a Router change and I actually lasted about 30 minutes making several attempts and was already angry about not getting it.
Of the 4 Ai Prime I have 2 I managed to reset after several attempts and the other two was more difficult, but in general I only had to remove the lights from my account, then use the button you mentioned in several ways, the one that worked was When I left it pressed and the light began to blink, I released the button and then pressed it once more and immediately released it. That's how I did it, but it really was very difficult.