The Myst games are designed such that there should never be any dead ends like those in the older Sierra adventures.
There are two reset levers for the generator if you sent too much power to it. If you follow the cables leading into the rocketship backwards, you should see two towers you can climb.
The way down to the first tower is just before the path to the rocketship. The second tower is near the entrance to the generator. All you have to do is climb both of the towers and flip whichever switch that is off back to "on" to restore power to the generator. Hope this helps.
