Не только не нашёл шифр, но и сломал рычаг.

Because they are doing two different jobs.

• The first не is part of the fixed expression не только ..., но и ... = not only ..., but also ...
• The second не negates the verb нашёл = found

So the pattern is:

• не только не нашёл X, но и Y
• not only did [someone] not find X, but [he] also Y

This is a very normal Russian structure.

It is a common paired construction used to connect two parallel ideas:

• не только ..., но и ... = not only ..., but also ...

In this sentence, the two parallel parts are verbs:

• не нашёл = didn’t find
• сломал = broke

So the sentence means something like:

• He not only didn’t find the cipher, but also broke the lever.

Very often this structure suggests that the second thing makes the situation even worse.

Russian often leaves out subject pronouns when the context makes the subject clear.

So instead of saying:

• Он не только не нашёл шифр, но и сломал рычаг.

Russian can simply say:

• Не только не нашёл шифр, но и сломал рычаг.

One important detail: Russian past tense forms like нашёл and сломал show gender and number, but not person. So by themselves they mean masculine singular past, which could refer to I, you, or he, depending on context. In most translations of an isolated sentence like this, it is usually understood as he.

Both are:

• past tense
• masculine singular
• perfective

More specifically:

• нашёл = past tense of найти (to find)
• сломал = past tense of сломать (to break)

Because they are masculine singular, they would change like this:

• masculine: нашёл, сломал
• feminine: нашла, сломала
• neuter: нашло, сломало
• plural: нашли, сломали

Because the sentence talks about completed results.

• не нашёл means did not find / failed to find
• сломал means broke in the sense of causing a completed result

Perfective is natural here because the speaker is talking about the outcome of the situation:

• the cipher was not found
• the lever ended up broken

If you used imperfective forms, the meaning would shift toward process, repetition, or a less result-focused viewpoint.

They are in the accusative case because they are direct objects, but for inanimate masculine singular nouns, the accusative looks exactly like the nominative.

So:

• шифр

  • nominative: шифр
  • accusative: шифр

• рычаг

  • nominative: рычаг
  • accusative: рычаг

That is why they appear unchanged.

In this kind of sentence, не нашёл often has a strong result meaning:

• didn’t find
• failed to find
• didn’t manage to find

Because the verb is perfective, it focuses on the final outcome: after trying or searching, the result was negative.

So in many contexts, failed to find is a very natural English interpretation.

Not completely. Russian word order is flexible, but this version is natural and clear:

• Не только не нашёл шифр, но и сломал рычаг.

This order keeps the two actions parallel:

• не нашёл
• сломал

If you change the word order, the basic meaning may stay the same, but the emphasis can shift. Russian often uses word order to highlight what is new, important, or contrastive.

Because the full paired construction is normally:

• не только ..., но и ...

The и adds the sense of also / too. So:

• но = but
• но и = but also

That is why the sentence has:

• не только ... , но и ...

rather than just не только ... , но ...

The ё shows both pronunciation and stress:

• нашёл is pronounced with stress on ё

In many Russian texts, ё is often written as е, so you may see нашел. But for learners, writing ё is very helpful because it makes the pronunciation clearer.

So:

• нашёл = learner-friendly, fully marked spelling
• нашел = common in everyday writing, but same word