iphone 3gs 16gb white parts repair read add ?

iphone 3gs 16gb white unlocked cracked the screen about 3 weeks ago on holiday came back and spent £50 on parts new screen and complete back housing tried to fix it myself however the screen now shows all white you can hear sounds in background but unsure what the problem is aloso will need new antenna cable as i damaged it while trying to put screen you can buy these off ebay for a few pound.. i can guarantee the phone is not barred or doesnt recieve service it was a replacement for apple and it fully genuine.. just want to sell the phone bought a new iphone 4. £80 no offers