What could be wrong with the iPhone?

So I took the iPhone with someone (an establishment in a mall) to get it fixed because the screen was broken. I picked it up and the guy said everything was fine and nothing was wrong. Obviously I believed him. So I went on my way and when I arrived home, I tried connecting it to my Wi-Fi and to my neighbors Wi-Fi and nothing! It wouldn't even find my house Wi-Fi. I went real close to my DSL and that's when it found the Wi-Fi. What could be wrong? What did the guy who fix the screen, mess up?

I'm considering taking it tomorrow first thing in the morning!

Certified Pre-owned Iphone 4?

I recently ordered the Pre-owned Iphone 4 from Verizon, I was just wondering, what will it look like, will it be clean? Also, what will come with it. I have never got a Certified Pre-owned phone before so I'm not sure what to expect.

Is my iphone 5 battery dead?

Hi, i have a problem with my iphone 5.
I can't charge it whatsoever. I tried different wall sockets and all that it just don't charge. The usb is not the problem because when my iphone is turned off and i plug the usb it opens the iphone but it won't charge it.
I managed to fix it twice by turning the phone off and changing the wall sockets but it gets really frustrating doing that over and over again and right now i can't even do it anymore.
So is there anything i can do to my iphone or is this a sign of a dead battery?

Can I upgrade and get a iphone early using verizon?

I had my phone for 2 years then it broke then i got a new phone and have had it for 6 months but i really want the iphone 5s like so badly would i be able to upgrade does the broken my phone still count because I had it for 2 years then it broke?

If I purchase an iPhone from Amazon?

Will I have to have a plan?
will I be charged monthly?

Added (1). When I went to the checkout, it didn't ask if I had a plan or wanted to create one?