Can you explain that ending?

The first hour of App was an original, surprisingly scary story of a mysterious app called Iris that seems to have downloaded itself onto college student Anna'a cell phone. What begins as mere annoyance quickly escalates into pure terror as the app takes over cameras, computers, email, and more, wreaking havoc on Anna's life.

Then, just as the film looks to be reaching new heights of intensity, it suddenly goes off the rails completely. In an effort to save her friend and find out who or what is behind the Iris app, Anna suddenly starts kicking everyone's ass. After her best friend Sofie is apparently killed by Iris in the swimming pool, Anna comes to suspect her ex-boyfriend is behind it all and shows up at his apartment to confront him. This is where everything goes to hell.

By the end it seems that the ex and Anna's brother's doctor are in cahoots together and the Iris app is an experiment to help Anna's brother walk again. What?! Then we learn that Leisbeth, the female voice we've heard coming from Iris, is actually the ex-boyfriend's dead girlfriend who we saw commit suicide at the beginning. What?! Iris also seemed able to predict the future. What?! The ex-boyfriend then loses it and kills the doctor. Finally, Iris, which has apparently been taken over by Liesbeth's ghost, seems to shoot the boyfriend through the phone. What?! The end.

App seems to have a lot of interesting but half-baked ideas that don't amount to much of an explanation. Was Iris controlled by the ex-boyfriend all along? Why were he and the doctor working together? How did Anna's brother fit in? Why was Iris killing people? How did the dead girlfriend Leisbeth take over the app? Did the app shoot the boyfriend or did the phone just explode? What the hell is going on in this movie?!

After a very promising 50-60 minutes, everything goes to hell. I had a dozen questions and no decent answers. It was like the first season of Lost all over again. Can anyone explain this damn movie?