Do va li bị móp nên tôi điền vào biên bản.

It is a cause-and-result pattern:

• do = because of / due to
• nên = so / therefore

So Do va li bị móp nên tôi điền vào biên bản has the structure:

• cause: va li bị móp
• result: tôi điền vào biên bản

A very close equivalent is Vì ... nên ....
Compared with vì, do often sounds a bit more formal or written.

You can omit one of them, and the sentence can still sound natural.

Common options:

• Do va li bị móp, tôi điền vào biên bản.
• Va li bị móp nên tôi điền vào biên bản.
• Vì va li bị móp, tôi điền vào biên bản.
• Tôi điền vào biên bản vì va li bị móp.

Using both do and nên makes the cause-result relationship very explicit.

Bị often shows that something is affected in an unwanted way.

Here, va li bị móp suggests:

• the suitcase got dented, or
• the suitcase was dented, with a negative sense

Compare:

• Va li móp = the suitcase is dented
• Va li bị móp = the suitcase was/got dented, and this is seen as an unfortunate result

So bị adds the idea that the suitcase suffered damage.

It behaves a lot like a stative verb or adjectival verb in Vietnamese.

That means Vietnamese does not need a separate word like to be before it.

So:

• va li móp = the suitcase is dented
• va li bị móp = the suitcase got/was dented

English forces you to choose between adjective-style and verb-style wording, but Vietnamese is more flexible here.

Vietnamese often does not use a copula like English is/was before adjectives or stative words.

So instead of saying something like the suitcase is dented, Vietnamese can simply say:

• va li móp

And with bị:

• va li bị móp

Tense is usually understood from context. If needed, Vietnamese can add time or aspect words such as:

• đã = already / past
• đang = in progress
• rồi = already

But in this sentence, no extra tense marker is necessary.

Because va li here is just being used as a plain noun.

Vietnamese does not require articles like a or the the way English does.
It also does not always need a classifier.

You would usually add a classifier only in certain situations, such as counting or pointing out a specific item:

• một cái va li = a suitcase
• cái va li đó = that suitcase

But in a sentence like this, just va li is perfectly normal.

Điền means to fill in information, and vào means into.

So điền vào biên bản literally means something like:

• fill into the report/document

In natural English, that often becomes:

• fill in the report
• enter the details into the report

The word vào helps show that information is being put into a document or form.

It is understandable, but depending on the situation, other verbs may be more idiomatic.

For example:

• ghi vào biên bản = write/record in the report
• lập biên bản = make up / draw up an official report
• viết biên bản = write a report

So:

• If you mean filling in a prepared form, điền vào biên bản can work.
• If you mean officially recording the incident, lập biên bản or ghi vào biên bản may sound more natural.

Biên bản usually means an official written record, report, or minutes.

It is often used in formal contexts such as:

• airlines
• police
• workplaces
• inspections
• accidents
• complaints

So it is more official than a casual note.

Depending on context, English translations could include:

• report
• record
• incident report
• written statement

Yes, absolutely. That is very natural.

Compare the focus:

• Do va li bị móp nên tôi điền vào biên bản
  = starts with the reason, so it highlights the cause first

• Tôi điền vào biên bản vì va li bị móp
  = starts with I, so it feels a bit more straightforward in conversation

Both are correct. The difference is mostly about emphasis and style.

Both can mean because.

In many cases they are interchangeable:

• Do va li bị móp nên tôi điền vào biên bản
• Vì va li bị móp nên tôi điền vào biên bản

A useful general guideline:

• vì = very common and neutral in everyday speech
• do = often a little more formal or written, especially in patterns like do ... nên ...

So a learner will probably hear vì more often in normal conversation, but do is still completely correct.