These are not possible.
God is infinite goodness itself. Any offense against Him is an offense of infinite magnitude, and deserving of an infinite degree of punishment. Therefore, any finite punishment would not be sufficient to account for the justice due for even the smallest sin.
The fact that we are forgiven at all is a gift of infinite measure, completely undeserved and born of God’s love for us. However, once a soul is in Hell, they are unwilling to be forgiven. Should a soul in Hell repent, they would be forgiven, and welcomed into Heaven. The reason this cannot happen is that when we die, we make a final decision, either for or against God. That decision is so complete in its scope and knowledge that it essentially locks us into that state. A soul who chooses for God would never sin against Him any further because we would never do anything to jeopardize the Beatific vision. The soul who chooses against Him becomes completely absorbed into itself, it would rather worship itself than God, and would therefore never do anything to jeopardize this self-worship.