The dialectic of planetary creation is dominated by two main forces: the loss of lighter elements of the primary atmosphere due to atmospheric escape, and the "ice line" within which water is less common.
For a habitable world it seems to be preferable for plate tectonics renew the atmosphere, which requires a large core, which requires relatively reducing conditions (lack of oxygen/water) so that iron interacts less in the mantle and sinks to the center.
For this reason, a planet near the sun starting with a large amount of steam and CO2 in the atmosphere sounds a bit off. Not tremendously unlikely, since planets migrate, impacts happen, and none of these models come with a money back guarantee.
If the planet gets to a runaway greenhouse, it seems in dire trouble. Hydrogen will definitely be lost in preference to carbon and oxygen, so the planet will steadily dry out. By the time you get to the "last phase" (I assume you mean something like Venus) the planet could probably calcine its own lime, at least underground. Plate tectonics are unlikely (they need water). There may be an ocean of ringwoodite deep underground - even on Venus there may be ringwoodite and some circulation of the mantle, despite what I said - but how to get at it?
Still, there are options. Planets keep migrating in and out. Collisions happen, even massive ones. The planet might lose much of its atmosphere because it's a little smaller than Venus, then it begins outgassing again. Perhaps it becomes tidally locked over time and the dark side is able to accumulate water.
My favorite for today is to suppose that the first two papers I quoted are right, and a planet in the position of Mars usually becomes depleted of oxygen in its atmosphere by the abundant iron and lack of plate tectonics, and develops dust storms like Mars, and sprays out a zodiacal light all over its star system like Mars. And in this light, there are primitive organisms that evolved during the first flush of its youth -- or life landed on it from the dust of other Mars clones caught in comets that had been in the Oort clouds of passing stars. Just so, life is available to all these worlds in rudimentary form, and on this one, it gets especially lucky in the comfortable outer layers of the atmosphere. These life forms do what you then want - they terraform your version of Venus. They manage to extract carbon into some kind of fireproof diatomaceous earth that rains down on the planet until it is cooler. They pull water out of sulfuric acid or find it deep underground and continue until the plate tectonics starts renewing the crust. Just so the Fravashis who play in our game of stellar conquest have ensured that even "acid worlds" will have some representation in the events that follow.