Learn Hardcore German: Drück bitte die Taste oben rechts, sonst startet das Gerät nicht. - Please press the button at the top right, otherwise the device won’t start.

Because this is the imperative for du. The usual du-imperative is just the verb stem: drück. The ending -e is optional: Drücke is also correct but sounds a bit more formal or old-fashioned. Drückst is only for statements/questions with du, not for the imperative.

How do I say this politely or to more than one person?

Polite (Sie): Drücken Sie bitte die Taste oben rechts, sonst startet das Gerät nicht.
Plural (ihr): Drückt bitte die Taste oben rechts, sonst startet das Gerät nicht.
Sign or instruction style: Bitte die Taste oben rechts drücken.

Where can I put bitte in this sentence?

It’s flexible: Bitte drück die Taste…, Drück bitte die Taste…, or Drück die Taste bitte… all work. Position changes tone slightly (initial or final feels extra polite), but the meaning stays the same.

Do I need auf, as in “press on the button”: auf die Taste drücken?

With Taste, German typically uses a direct object: eine Taste drücken (no preposition). With Knopf, auf den Knopf drücken is very common. You’ll hear auf die Taste drücken too, but the bare object is the default.

What’s the difference between Taste and Knopf?

A Taste is a flat “key” (like on keyboards or device panels). A Knopf is a (push)button or knob. In everyday speech people may say Knopf for many physical buttons; both will be understood. Note the articles: die Taste (acc.), but den Knopf (acc., masculine).

What does oben rechts modify here—the verb or the noun?

It specifies which button and belongs to the noun phrase: die Taste [oben rechts]. It’s an adverbial attribute to the noun, not an adverb to the verb. There’s no comma.

Can I say rechts oben or use adjectives like die rechte obere Taste?

Yes. rechts oben is just as common as oben rechts. As an adjectival version you can say die rechte obere Taste (upper-right button), which sounds a bit more formal/technical.

Why is it sonst startet das Gerät nicht and not sonst das Gerät startet nicht?

German main clauses follow the verb-second rule. Sonst sits in the first position, so the conjugated verb (startet) must be second: sonst startet…. Putting das Gerät before startet after sonst breaks that rule.

Why nicht and not kein?

Use nicht to negate a verb or the whole clause: startet nicht. kein negates a noun phrase: kein Gerät (= no device).

Where does nicht go in this clause?

In a simple main clause it typically goes near the end: … startet das Gerät nicht. It can move earlier for emphasis or when specific elements are negated, but this is the neutral position.

Is the comma before sonst required?

Yes. You’re separating two main clauses. Sonst is a conjunctive adverb (“otherwise”), and German uses a comma to mark the clause boundary.

Is starten idiomatic here? What are alternatives?

Yes, starten is fine for many devices. Alternatives: … geht (nicht) an (won’t turn on), for computers … fährt (nicht) hoch, for engines … springt (nicht) an. Choose what matches the device.

What are the genders and cases of Taste and Gerät here?

die Taste (feminine) is accusative singular as the direct object of drücken. das Gerät (neuter) is nominative singular as the subject of startet. Plurals: die Tasten, die Geräte.

Spelling: drücken vs. drucken?

Different verbs. drücken (with ü) = to press; drucken (with u) = to print. Don’t drop the umlaut: if you can’t type it, write druecken/drueck.

Can I drop bitte, or soften it in another way?

You can omit it: Drück die Taste…. A common softener is mal: Drück mal die Taste…. You can also combine: Bitte drück mal… for a friendly tone.

Could I use wenn nicht or ansonsten instead of sonst?

Yes. Examples: Drück bitte die Taste…, wenn du das nicht machst, startet das Gerät nicht. or … , ansonsten startet das Gerät nicht. sonst is the most concise.

How do you pronounce ü in drück and ä in Gerät?

ü is a front, rounded vowel—say English “ee” while rounding your lips: [y]. ä in Gerät is a long “eh” sound: [eː].