sony ericsson equinox help!!?

['thatzninjae']

I just got a Sony Ericsson Equinox from my grandma last week, brand new, she got it for an exchange from t-mobile and decided to keep her old phone and since my phone's keyboard was shot she gave me that phone... well I tried sending a text to my friend today , it errored out so I open the phone and it said inactive sim so I take out the battery and sim card, I put them back and turn the phone on.. well now the screen won't turn on.. the keyboard lights up halfway, nothing works.. it acts like its not even turned on...... is it worth fixing or what... someone's who good with phones what do you think could be wrong with it.. ?