Learn Hardcore French: Le bouton ne réagit pas; appuie doucement une deuxième fois. - The button is not responding; press gently a second time.

A semicolon in French links two closely related independent clauses: the first states a situation, the second gives a consequence or instruction. You could also write a period, or use a comma plus a connector like donc/alors. A bare comma between full clauses is less common in careful French.

How does the negation in ne réagit pas work? Can the ne be dropped?

Standard written French frames the verb with ne … pas: ne
- réagit
  - pas.
In casual speech, many speakers drop ne: Le bouton réagit pas. Keep ne in formal writing.

Is réagir the best verb here? What about répondre or fonctionner?

Réagir is idiomatic for interfaces/devices that don’t respond to input.
Répondre also works for responsiveness: Le bouton ne répond pas.
Fonctionner is broader, “to work/function”: Le bouton ne fonctionne pas suggests it’s broken, not just slow.

Why is there no final -s in appuie?

It’s the imperative of an -er verb. In the 2nd person singular imperative, -er verbs drop the final -s: tu appuies (present) → appuie (imperative). Note: you keep the -s before the pronouns y/en for euphony (e.g., Manges-en), but that doesn’t apply here.

Can I use appuyez instead of appuie?

Yes. Appuie addresses one person you tutoyer (informal). Appuyez is for plural or polite vous: Le bouton ne réagit pas; appuyez doucement une deuxième fois.

Do I need sur or dessus after appuie?

The full form is appuyer sur: Appuie sur le bouton.
If the object is obvious, French often omits it in instructions: Appuie doucement (i.e., “press it gently”).
To avoid repeating le bouton, you can say Appuie dessus (“press on it”).

Why doucement and not doux? And how is it different from lentement?

Doucement is the adverb (“gently/softly”) formed from doux/douce; adjectives (doux/douce) don’t modify verbs.
Lentement means “slowly” (speed), not “gently” (force). For buttons, doucement is the natural choice.
You can also say en douceur (“gently”): Appuie en douceur.

What’s the nuance of une deuxième fois vs deux fois vs la deuxième fois?

Une deuxième fois = “once more/a second time from now.” It tells you to repeat one time.
Deux fois = “twice (in total).” It could be read as “press two times,” not “press again once.”
La deuxième fois refers to “the second occasion/time” in a sequence, not an instruction to repeat now.

Can I say seconde instead of deuxième?

Often yes: une seconde fois is idiomatic. Traditional nuance: second(e) implies there are only two, while deuxième doesn’t. In practice, deuxième is more common and neutral.

What are the genders of bouton and fois, and do the articles match?

Bouton is masculine: le bouton.
Fois is feminine: une fois, la fois (but with numbers you typically say deux fois, trois fois without an article).

Can I move doucement elsewhere, like Appuie une deuxième fois doucement?

Yes. Both Appuie doucement une deuxième fois and Appuie une deuxième fois doucement are acceptable. The first slightly emphasizes the manner (“gently”) before the count; the second emphasizes the repetition and then the manner. Style choice more than a rule.

Should there be a space before the semicolon in French?

Yes. French typography uses a (usually non-breaking) thin space before ;, :, !, ?. In plain text you’ll often just see a normal space: Le bouton ne réagit pas ; appuie… Many people omit it online, but the typographic norm includes it.

Does réagir need à (as in réagir à) here?

Not necessarily. Réagir often takes à when you name the stimulus (réagir à la chaleur), but it’s fine intransitively when the context is clear: Le bouton ne réagit pas (to being pressed).

Could I say presser instead of appuyer?

You’ll be understood with presser le bouton, but everyday French strongly prefers appuyer (sur) le bouton for “to press a button.”
Presser is more formal/literary or used in other senses (to squeeze, to hurry).