Мало того что я забыл проездной дома, так ещё и телефон разрядился.

It is an emphatic structure used to pile one problem on top of another.

A natural English equivalent is something like:

• It wasn’t enough that ...; on top of that ...
• As if ... weren’t bad enough, ... too
• Not only ..., but ... as well (but with more emotion)

So this sentence does not just list two facts. It sounds like a complaint: one bad thing happened, and then another bad thing happened too.

Here так is part of the larger pattern мало того что ..., так ещё и .... It helps introduce the second, additional problem.

By itself, так often means so, thus, or like this, but in this construction it is not really translated word-for-word. It mainly strengthens the connection:

• мало того что ... = it’s bad enough that ...
• так ещё и ... = and on top of that ...

You will sometimes hear shorter versions without так, but with так the pattern sounds very natural and emphatic.

In this sentence, ещё и means something like:

• also
• even
• on top of that

The и adds emphasis. Compare:

• ещё = still / yet / more
• ещё и = and also / even as well

So так ещё и телефон разрядился is stronger than just saying телефон разрядился.

Проездной is a very common short form of проездной билет.

It means a travel pass or transit pass: for example, a bus pass, metro pass, or monthly public transport pass.

Russian often drops the noun билет because the meaning is clear from context. So:

• проездной билет = travel pass
• проездной = same thing, just shorter and more common in everyday speech

Because проездной is the direct object of забыл.

The verb забыть / забыл takes the accusative case. For a masculine inanimate noun, the accusative singular looks the same as the nominative singular.

So:

• nominative: проездной
• accusative: проездной

That is why the form does not visibly change.

No. Here дома is an adverb, meaning at home.

So:

• дóма = at home
• домá = houses

They are spelled the same, but the stress is different.

In this sentence, забыл проездной дома means left/forgot the travel pass at home.

Because дома is already an adverb, not a noun phrase.

Russian often uses дома by itself to mean at home, without в:

• Я дома = I am at home
• Я оставил это дома = I left it at home
• Я забыл проездной дома = I forgot/left my travel pass at home

If you used a noun phrase instead, then you would need a preposition:

• в доме = in the house

But that would mean something different.

Because both verbs describe completed events with results that matter now.

• забыл = forgot / left behind
• разрядился = ran out of charge / died

The perfective aspect is very natural here because the speaker is talking about specific completed mishaps.

If you used imperfective forms, the meaning would change and would sound less natural in this context, unless you were describing a repeated or background situation.

Yes. In everyday Russian, it is very normal to say that a phone разрядился.

The verb разрядиться literally means to become discharged or to run out of charge. Russian often treats the device itself as the thing that ran out of power.

So:

• Телефон разрядился = The phone died / ran out of battery.
• Батарея разрядилась = The battery ran down.

Both are possible, but телефон разрядился is extremely common.

The -ся form here does not mean a person did something to themselves. It is just the normal intransitive verb form: to discharge / to run down.

Russian often leaves possession unstated when it is obvious from context.

Since the first clause already has я, it is clear whose phone is meant. So телефон разрядился naturally means my phone died in this context.

You could say:

• так ещё и мой телефон разрядился
• так ещё и у меня телефон разрядился

But those versions are more explicit. The original is shorter and very natural.

The main comma separates the two clauses:

• Мало того что я забыл проездной дома, так ещё и телефон разрядился.

Here мало того что functions as one connective introducing the first clause, and the comma comes before the second part, так ещё и ...

You may sometimes also see related punctuation patterns in other sentences, especially when a writer wants a stronger pause, but the version you were given is standard and natural.

It is natural everyday Russian and sounds mildly conversational.

The structure мало того что ..., так ещё и ... is common when someone is complaining, expressing annoyance, or emphasizing that one problem was followed by another.

A more neutral version might be something like:

• Я забыл проездной дома, и к тому же у меня разрядился телефон.

That sounds less emotional.

Yes, Russian word order is flexible, but changing it changes the emphasis.

The given order is very natural because it presents the first problem and then adds the second one dramatically.

For example, you could also hear:

• Мало того что я дома забыл проездной, так ещё и телефон разрядился.

This is still understandable, but the focus shifts a little.

In the original, забыл проездной дома sounds smooth and idiomatic, with the main stress usually falling on the bad outcomes: forgetting the pass and the phone dying.