When you say the wood is peeling back, you mean the layers of plywood have separated, it has delaminatedl?
You're going to have to take the electric steps off for any repair. They're heavy and not well balanced, a floor jack really helps. Power disconnected before you start anything.
If the bad wood rests on a metal framework it's relatively easy, get the old out and replace it with new. A couple of good coats of paint, rubberized water proofing, flashing on the bottom will help.
If there is no framework I would make a wide L bracket of light steel and hang the new step from the vertical wood if it's solid enough.