App crashes every time I open it on iPad 1 iOS 5.1.1?

(Repost because it was left unanswered for two days straight, please READ every single detail)

Let's start from the beginning: Somewhere in 2013 I downloaded an app called QuizUp on my iPad 5.1.1. It was version 1.3.5 and it worked great. Just now recently I started playing QuizUp again but on my iPhone iOS 8.2. The version is now 2.0 and a lot of hacks were patched.

I saw a video where you can hack it with Cydia on the old version, so I jailbroken my device. Before I jailbroke my device, I checked if QuizUp 1.3.5 was still working and it was, I even played with other peeps. Once I jailbroke it I lost all my apps. So I went to App Store > Purchased > QuizUp. It asked me: "Do you want to download an older version of this app?" I clicked on Download and it downloaded just fine, with version 1.3.5. But when I open it it, the app crashes immediately.

I already did a reboot holding down the power and home button but it didn't seem to work. I've also tried resetting factory settings, soft reset, and reinstalling it. Help, please? I've been dealing with this the whole week, and I don't want to waste my summer trying to fix this with no end.

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