Jag såg på skärmen att batteriet inte började ladda.

Såg is the past tense of se (to see).

The sentence describes something the speaker noticed at a particular moment in the past, so Swedish uses the simple past:

• se = to see
• ser = see / sees
• såg = saw
• sett = seen

So Jag såg means I saw.

In this sentence, it means I saw on the screen.

That is, the screen is where the speaker got the information. The structure Jag såg på skärmen att ... is naturally understood as I saw on the screen that ...

A small nuance:

• se på can sometimes mean look at or watch
• but with an att-clause after it, the meaning here is clearly see from/on the screen that ...

So in this sentence, på skärmen tells you where the evidence appeared.

Swedish normally uses på for something shown on a screen, just like English usually says on the screen.

• på skärmen = on the screen
• i skärmen would sound more like inside the screen, physically in it, which is not what is meant here

So på skärmen is the natural choice.

Batteriet is the definite form, meaning the battery.

Swedish often adds the definite article as an ending:

• ett batteri = a battery
• batteriet = the battery

Here, the speaker is talking about a specific battery that is already identifiable from the situation, so the definite form is used.

Here, att means that, not to.

It introduces a subordinate clause:

• Jag såg ... att batteriet inte började ladda
• I saw ... that the battery did not start charging

Swedish att can have two different jobs:

1. that as a conjunction

   • Jag vet att han kommer = I know that he is coming

2. to as an infinitive marker

   • Jag vill att läsa is wrong, but historically/elsewhere att can appear before an infinitive in some contexts such as börja att läsa

In your sentence, it is definitely the first one: that.

Because this is a subordinate clause after att.

In Swedish, word order changes in subordinate clauses. The usual pattern is:

• att
  • subject + inte
    • finite verb

So here you get:

• att batteriet inte började ladda

Compare that with a main clause:

• Batteriet började inte ladda.

So:

• main clause: finite verb usually comes before inte
• subordinate clause: inte usually comes before the finite verb

This is one of the most important Swedish word-order rules to learn.

Because började ladda means started charging or began to charge, while laddade inte would mean was not charging / did not charge more generally.

So there is a difference in focus:

• batteriet började inte ladda = the charging process failed to start
• batteriet laddade inte = the battery was not charging

The sentence specifically focuses on the beginning of the process, so började ladda is the better choice.

Yes. In everyday Swedish, especially in tech contexts, ladda is often used intransitively to mean charge / be charging.

Examples:

• Telefonen laddar. = The phone is charging.
• Batteriet började ladda. = The battery started charging.

You can also use ladda transitively:

• Jag laddar batteriet. = I am charging the battery.

A more formal or explicitly passive-style version might be:

• batteriet började laddas

But the version in your sentence is very common and natural in everyday language.

It has two parts:

1. Main clause
   Jag såg på skärmen
   = I saw on the screen

2. Subordinate clause
   att batteriet inte började ladda
   = that the battery did not start charging

So the full structure is:

• Jag = subject
• såg = finite verb
• på skärmen = adverbial of place/source
• att = subordinator
• batteriet = subject of the subordinate clause
• inte = sentence adverb
• började = finite verb
• ladda = infinitive

This is a very typical Swedish sentence pattern.

Yes, if the context already makes it clear.

You could say:

• Jag såg att batteriet inte började ladda.

That means I saw that the battery did not start charging.

Adding på skärmen simply makes the source of the information more specific: the speaker saw this on the screen, not for example by touching the device or noticing some other physical sign.

Yes. That is also correct.

Swedish main clauses follow the V2 rule, which means the finite verb comes in the second position. So if you move På skärmen to the front, the verb must still stay second:

• Jag såg på skärmen att ...
• På skärmen såg jag att ...

Both are grammatical. The second version puts a little more emphasis on på skärmen.