Learn Dutch: Het scherm was zwart tijdens de storing. - The screen was black during the malfunction.

Tijdens works exactly like the English word "during". It is a preposition of time, which means it must be followed by a noun or noun phrase (like de storing in this sentence). You cannot use it to introduce a whole new clause with a subject and a verb.

Does storing always mean "malfunction"?

Usually, yes. It translates to "malfunction", "fault", "glitch", or "disruption". It is widely used in tech contexts (like a black screen or internet outage) and public transport (like a signal failure on the railway). The root verb is storen, which means "to disturb" or "to interfere".

Why use was (was) instead of werd (became) if the screen turned black?

The sentence uses was because it describes an ongoing state: how the screen looked while the malfunction was happening. If you wanted to focus on the change and say the screen went or turned black, you would use werd (the past tense of worden, meaning "to become").

Could I put tijdens de storing at the beginning of the sentence?

Yes, you can! But remember that moving a time phrase to the first position triggers inversion, meaning the verb must come before the subject. It would become: Tijdens de storing was het scherm zwart.