Does the Bible provide any passages that might help in understanding how Satan became sinful?

Satan (the Enemy, Adversary, Evil One, etc) never rebelled against God, nor was he (to our knowledge) ever in Heaven or an Angel. The Isaiah 14:12-13 verse is not talking about Satan at all. The word "Lucifer" is derived from the latin "lux ferre", which simply means "Bringer or Light" or "Bringer of Dawn" or similar incantations depending on who you ask.

This passage, instead, is talking about the King of Tyre. I have found it has been completely ignored that the following verses state this prophecy is about A MAN - how could Satan be both an angel and a man? He couldn't.

Christ, in Matthew, could be making a prophetic statement to Revelation - when the Dragon is cast from Heaven - and with the authority to trample coming from the different plagues which are instructed not to harm the true believers.

There is no Biblical basis for Satan ever being more than he is, and to teach such goes against the Word of God as written by Paul -

"And these things, brethren, I have in a figure transferred to myself and to Apollos for your sakes; that ye might learn in us not to think of men above that which is written, that no one of you be puffed up for one against another." - 1 Cor 4:6 KJV

Sin has existed since the Creation. Man did not know it until Adam and Eve ate the fruit God instructed them not to eat. We must also accept that, as Sovereign Creator, God created evil as well - this is even written in Scripture!

I form the light, and create darkness: I make peace, and create evil: I the LORD do all these things. - Isaiah 45:7 KJV

If Satan were an angel, he would have no power to go against God's will - and thus could not rebel. This is why man was created, so we could have that choice and truly worship God in his glory.

So no, there are no passages to support a basis for Satan "becoming" sinful, because Satan is not necessarily sinful, but evil and a tempter - and he has always been that way as far as we are actually taught in the Word.

The Sin of Disobedience [stemming from] Pride (the one most oft stated)

It is assumed that the readers of this answer know of the Thomists vs. Scotists¹ motive for the Incarnation. They both tackle: Would the incarnation would not have taken place at all, had not man sinned? This answer adopts the Scotist view: Jesus Christ was the End of creation [without or with the fall of man].

From this answer [to] What biblical passage [or passages] reveals [or reveal] what God says was the fallen angels sin?, it has been noted that God not so much puts his free creatures to the test when he creates them, but rather enjoins them to obedience/obey a command. In the case of man, he was commanded not to eat of the tree of the knowledge of good and evil.

From scripture, the following appears to have been the command given the angels, after God revealed the end of creation to his heavenly court, when discussing [with them?] the creation man²:

And again, when he brings the first-born into the world, he says, “Let all God’s angels worship him.” [cf. Heb 1:6 (RSVCE)]

If the heavenly court comprised of the morning stars³, it seems one refused⁴ and instigated a rebellion among the other angels.

War broke out in heaven when Michael [Michael = in Hebrew, "Who is like God?"] with his angels attacked the dragon. The dragon fought back with his angels.⁵

1. [cf. Cur Deus Homo? The Motive of the Incarnation | Fr. George Florovsky]↩

2. [cf. Gn 1:26 (RSVCE). The Jerusalem Bible, Popular Edition footnote referencing the First account of creation of man God said, 'Let us make man in our own image, in the likeness of ourselves, [...]' has: Perhaps the plural of majesty: the common name of God was Elohim, a plural form. But possibly the plural form implies a discussion between God and his heavenly court. cf. Jb 1:6: One day the Sons of God [Footnote: The angels who make up his Council] came to attend on the LORD, and among them was Satan.]↩

3. Job 38:7 (RSVCE)]↩

4. Isaiah 14:12-13 (RSVCE)]↩

5. Revelation 12:7-8 (RSVCE)]↩

Endnote:

Just as it has been noted on the CHRISTIANITY StackExchange that there are common threads and recurring themes on gods across religions, demonology is no different.

cf. Yazidi's [t]hen God gave life to Adam from his own breath and instructed all archangels to bow to Adam[.] is very similar to the one in Devil (Islamic Theology).

The common thread and recurring theme being that sin of the devil is connected with man.

The Old Testament and apocrypha of the Bible, when read without the preconceptions of later centuries, give us some insight into how Satan became sinful, at least in belief.

In Job, Satan does the bidding of God. In chapter 1 we find Satan returning to the heavenly court, with news of his attempts to test the righteous. In Job 1:3, God says to Satan, "Hast thou considered my servant Job, that there is none like him in the earth, a perfect and an upright man, one that feareth God, and escheweth evil?" Jeffrey B. Russell says in The Prince of Darkness, page 37, Satan is already a personality with the function of accusing, opposing, and harming human beings, but he is not yet the principle of evil, for he is still one of the heavenly court and does nothing without God's consent and command. In Zechariah 3:1-2, Satan is likewise an accuser against Joshua but not yet an evil adversary of God.

Russell says (page 32) that the Jews of the Apocalyptic period (200 BCE to 100 CE) could not understand why God had abandoned Israel and allowed evil to rule the world in their time. Such a degree of evil was more than God would ordain and greater than mere humans could cause. It must therefore be the work of a powerful spiritual force. The Apocalyptic writers studied the Old Testament and found a hint of such a force in the sinful bene ha-elohim. They proceeded to develop these hints into full, colourful accounts, as in the Book of Enoch.

The Book of Enoch, part of the Ethiopian canon, but apocryphal in the west (although cited by Luke and Jude), tells of the sons of God in their fallen state and learns that these “angels, the children of heaven, saw and lusted after” the daughters of men. The Book of Enoch describes a leader of these 'Watcher' angels, who later became identified as Satan. As one of the Watcher angels, Satan's lust was what at first drove him to evil. Rabbinical Judaism eventually rejected the concept of Satan as an evil being, but not before he was adopted by Christianity.

Other traditions developed over time, with 2 Enoch saying that Satan naively thought that he could be greater than God, with his pride leading to rebellion and then expulsion from heaven.

This seems like your main question:

"But if God created Satan (originally) as a good (i.e., sinless) being who only entertained good thoughts, what was the original cause of Satan's evil or sinful thoughts?"

That's tough to find a scriptural answer to because the first historically noted thing about Satan was that he was proud.

Isaiah 14:12,13 KJV How art thou fallen from heaven, O Lucifer, son of the morning! how art thou cut down to the ground, which didst weaken the nations! For thou hast said in thine heart, I will ascend into heaven, I will exalt my throne above the stars of God: I will sit also upon the mount of the congregation, in the sides of the north:

Luke 10:17-19 NIV The seventy-two returned with joy and said, “Lord, even the demons submit to us in your name.” He replied, “I saw Satan fall like lightning from heaven. I have given you authority to trample on snakes and scorpions and to overcome all the power of the enemy; nothing will harm you.

There's no historical details given about him before he succumbed to pride. This passage from James seems to say that it's one's evil desires that produce sin:

James 1:13-15 NIV When tempted, no one should say, “God is tempting me.” For God cannot be tempted by evil, nor does he tempt anyone; but each person is tempted when they are dragged away by their own evil desire and enticed. Then, after desire has conceived, it gives birth to sin; and sin, when it is full-grown, gives birth to death.

One could argue that evil desire causes pride, but you could say also that pride causes evil desire. God's word is intentionally ambiguous on this so one can't be dogmatic. And this still doesn't answer the question of how a sinless Lucifer could have gotten evil desires/pride in the first place.

But here's what we DO know:

1. God created Satan
2. Satan was tempted by power and...
3. Satan did succumb to that temptation.

God must have therefore created Satan with this ability to succumb to temptation, whether Satan was created sinless or not. Maybe God did all this to prove that anything outside his nature can succumb to evil, even his most gloriously created angel.