Why on earth would i want to spend £90 on a phone and break it so this would happen, you idiot!!!
Excuse me? I resemble that comment!
Connectors could be damaged by accident when putting the sim card in.
You should have checked it was working prior to leaving the shop seeing as you knew you were buying a 2nd hand phone.
I don't see why they SHOULD give you your money back in all honesty.
Chalk this one up to experience and let it be a lesson learned. I presume you are around 22 given your username so you have plenty more years ahead of you in which to be careful.