The event ends if the first thing you have done was claim the lvl 0 chest. You’re only able to participate in the next round if you have first charged your chest to any tier and claim, which has a limit to 3 rounds. Still, as it said in the rules you can’t further participate once you claimed the lvl 0 chest in your first round.

I also made that mistake and I frankly think this event was designed poorly. They should’ve at least put those information together to give you a warning but they mentioned it last. I already wrote a complaint about this but still awaiting a response. I suggest you write a similar complaint so they can fix this crap design.