Learn Turkish: Asansör bakımdan dolayı kapalı. - The elevator is closed due to maintenance.

The postposition dolayı means 'due to' or 'because of'. It always forces the word before it to take the ablative case suffix -DAn (meaning 'from'). Here, bakım (maintenance) takes the suffix -dan, creating the phrase bakımdan dolayı.

Can I use ötürü instead of dolayı in this sentence?

Yes! The postposition ötürü means the exact same thing and also pairs with the ablative case. bakımdan ötürü is perfectly correct, though dolayı is slightly more common in everyday conversation.

Is bakım related to the verb bakmak?

Yes. While bakmak generally means 'to look', it also means 'to look after' or 'to care for'. The suffix -ım turns the verb into a noun, giving us bakım, which means 'care' or 'maintenance'.

Where is the 'is' in this sentence? Shouldn't it be kapalıdır?

In spoken or everyday Turkish, the third-person 'to be' suffix -dır is frequently dropped. Stating kapalı on its own is completely natural and understood as 'is closed'. However, if you read this on a formal printed sign pasted on the elevator doors, it would very likely say kapalıdır.