Şarjım bitmişti, o yüzden sabah alarmım çalmamıştı.

In Turkish -mişti (root + -miş + -ti) marks the past perfect (pluperfect) or “had done” sense. Here you have two past events in sequence:

• şarjım bitmişti (“my battery had run out”) – Event A completed first
• alarmım çalmamıştı (“my alarm hadn’t gone off”) – Event B

Using simple past bitti (“it ran out”) wouldn’t clearly show that the battery dying happened before the alarm failure. Bitmişti emphasizes that one event was already finished when the next one occurred.

çalmamıştı is the negative past perfect (“had not rung”): • çal- (stem “to ring”)
• -ma (negation)
• -mış (experiential/past indefinite)
• -tı (past tense ending)

Combined, they mean “had not rung.”
On the other hand, çalmadı (root + -ma + -dı) is simple past negative (“didn’t ring”). It states a past fact but doesn’t emphasize that this non-ringing was already in effect before another past moment.

Both o yüzden and bu yüzden mean “so,” “therefore,” or “for that reason.”

• o yüzden literally “for that reason” (linking back to what was just said)
• bu yüzden literally “for this reason”

In everyday Turkish they’re largely interchangeable. O yüzden is slightly more common when you want to point directly to a previous clause.

Turkish word order is flexible. o yüzden can go:
• At the beginning: O yüzden sabah alarmım çalmamıştı.
• In the middle: Sabah alarmım çalmamıştı, o yüzden…
• Immediately before the verb: Sabah o yüzden alarmım çalmamıştı.

The main constraint is that the verb stays at the end. Shifting o yüzden slightly changes emphasis but not the core meaning.

To say “my alarm,” attach the 1st person singular possessive suffix -ım/im/um/üm with vowel harmony: • Noun: alarm
• Suffix: -ım (back vowel after a)
→ alarmım

You see two ms because the root ends in m and the suffix begins with m. Both consonants are pronounced (a geminated mm).

In Turkish it’s idiomatic to talk about şarj (“charge”) rather than the physical battery: • şarjım bitti = “my charge ran out” (common, focuses on lack of power)
• telefonumun pili bitti = “the battery of my phone died” (more formal/literal)
• pilim bitti = “my battery died” (acceptable, but can be less specific)

Using şarjım is the most natural way to say “my phone died because it lost its charge.”