Learn Turkish: Ampul hakkında bir kitap yazıldı. - A book about the light bulb was written.

The verb root is yaz- (to write). Because it ends in a consonant (other than L), we use the passive suffix -ıl based on 4-way vowel harmony. That gives us the passive stem yazıl- (to be written). Finally, we add the definite past tense suffix -dı to mean "was written".

Why doesn't bir kitap have an accusative object ending (like kitabı)?

In an active sentence, the book would be the object receiving the action. But in a passive sentence, the receiver of the action becomes the grammatical subject. Subjects in Turkish always stay in the bare (nominative) case, so bir kitap doesn't take an object marker.

Does the word hakkında (about) always follow a bare noun like it does with ampul?

Yes, for regular nouns like ampul (light bulb) or kitap (book), hakkında just follows the bare dictionary form of the word. You only need to use the genitive case before it when you are dealing with pronouns (like senin hakkında - about you) or specific people's names (like Ayşe'nin hakkında - about Ayşe).