My iPhone 5S is dead, please help

I got my iPhone 5S last year, now it has passed the 1-year period of warranty.

I have been using this iPhone 5S very carefully, always in great protection in case, and only used for making phone calls, text message, taking pictures and so on.

However yesterday it suddenly went dead, and no matter what I tried, it just couldnt be turned on. Yesterday afternoon I brought it to local Apple store. The tech guy told me to hold power and home button for 10s, but still couldnt be turned on, Then he asked me to bring home to charge more time. Today everything is still same and no hope. This evening I brought it to store again, and they tried with iTunes, and then said the problem is main board. I am so frustrated that I paid more money to buy it for its quality and after a year careful usage, and it went dead for such internal part that we never could open and touch, and they told me the failure is on me, and I had to pay to get another one. It really *****. It tell me that they sell it for big bucks and not let us touch anything inside, and when it failed, they try not to be responsible. yuck.

Can anyone give some other tips that i can try to make it work for a few more month until my contract is over? then I guess i am out of apple product, and also would share my experience with the friends around me. I guess no one want to pay high premium for product that people have no control but are responsible for the problem no matter how careful you are.