Alex’s translation questions the listener in the present; Elena’s about something that required a decision in the past.

In Russian, this idiomatic phrase typically questions about the present state of the listener.
However, it’s possible to imagine a situation in the past as well.

In the past event, this question would require MORE THAN TWO words:
A: Он на прошлой неделе сказал мне, чтобы я определился до конца вчерашнего рабочего дня.
Б: И ты определился?

That’s what I thought - just making sure. Your translation is correct.

Elena’s version in the past tense implies a context like «И что? Ты определился?» Again, more than 2 words.

Anyway, I don’t want to say that Elena’s translation is incorrect. It just implies a specific context.

Let’s call it a day, I’m off 😵😴

I agree 100%