[underlines]

afaik, guessing anything not 00000 or 11111 at first step will lead to an optimum strategy of 3 steps. because you introduce possible "right digit at wrong place" as a third state.

guessing 00000 or 11111 removes that third state and leaves you with simple substitution of wrong cells, which leads to an optimal 2 step strategy.

but obviously the shortest strategy is just guessing it right on the first try :D lol

[paxys]

It doesn't matter.

Right digit at the wrong place = wrong digit = you should flip it.

This puzzle won't take more than 2 guesses no matter what you input the first time.

[Jtsummers]

It's still two steps. You only ever need to flip wrong digits.