Apenas termina, vuelvo a desenchufar el microondas.

Here it means as soon as (i.e., the moment something finishes). When apenas starts a time clause and there’s a comma after it, it’s temporal: Apenas termina, … = “As soon as it finishes, …”

• Barely/hardly is another meaning of apenas, but you’ll see it in contexts like Apenas tengo tiempo (“I barely have time”) or Apenas si comí (“I hardly ate”).
• If you want an unambiguous alternative for “as soon as,” you can use en cuanto or tan pronto como.

Both exist, but they’re used a bit differently:

• Apenas termina, … (indicative) = habitual or routine: “Every time it finishes, I …”
• Apenas termine, … (subjunctive) = a specific future event: “As soon as it finishes (this time), I …” In Latin America, you’ll hear both; if you mean a one‑off future action, apenas termine is the safer choice.

In Spanish, time clauses introduced by cuando, en cuanto, tan pronto como, apenas, etc., normally use the present (indicative or subjunctive) to refer to future time. So:

• Apenas termine, lo desenchufo. = “As soon as it finishes, I’ll unplug it.” You can also use the future in the main clause if you like: Apenas termine, lo desenchufaré.

Volver a + infinitive means to do something again. So vuelvo a desenchufar = “I unplug again.”

• Natural alternatives: lo desenchufo otra vez / lo desenchufo de nuevo.
• There’s no difference in meaning; volver a is just a common, compact way to express repetition.

Both positions are correct:

• Before the conjugated verb: Lo vuelvo a desenchufar.
• Attached to the infinitive: Vuelvo a desenchufarlo. With commands: Desenchúfalo de nuevo (affirmative), but No lo vuelvas a desenchufar (negative).

Microondas is masculine: el microondas. The word is invariable: singular and plural look the same.

• Singular: un/el microondas
• Plural: unos/los microondas

When a subordinate time clause comes first, Spanish typically uses a comma to separate it from the main clause:

• Apenas termina, vuelvo a desenchufar… If the main clause comes first, you usually don’t put a comma:
• Vuelvo a desenchufar el microondas apenas termina.

Yes:

• Vuelvo a desenchufar el microondas apenas termina. (habitual)
• Vuelvo a desenchufar el microondas apenas termine. (specific future) No comma is needed when it’s at the end.

Spanish often drops subject pronouns. Here, termina refers to the contextually obvious subject—likely “the microwave cycle,” “the heating,” or just “the microwave.” You could make it explicit:

• Apenas termina el ciclo, …
• Apenas termine de calentar, …

Both can mean “to end/finish.” In many places, terminarse is a common pronominal variant and sounds natural: Apenas se termina, … Subtle tendencies:

• Terminar (intransitive) for events ending: Terminó la película.
• Terminarse often for things “running out” or finishing up: Se terminó la batería. But in everyday speech, for processes like a microwave cycle, both are heard.

The “as soon as” use of apenas is widely understood across Latin America (e.g., Apenas llegó, llamó). If you want to avoid any chance of ambiguity, en cuanto or tan pronto como are crystal clear everywhere:

• En cuanto termine, lo desenchufo.
• Tan pronto como termine, lo desenchufo.

Slightly:

• Apenas termine, lo desenchufo. = immediate intention/plan; very natural.
• Apenas termine, lo desenchufaré. = also correct; can sound a bit more formal or detached. Both communicate a future action; the difference is stylistic.