I have messed up my old iPhone 3GS. Some time ago I did a battery replacement which requires mostly dismantling the phone. However, all went well and it worked fine. Recently though, I got a SIM card stuck in the tray, and the only solution was to dismantle it again. This time however, all didn't go well. None of the speakers work; the earpiece, external speakers or the headphone jack. I've reattached the tricky cable 3 many times and it seems fine. Does anybody who has repaired a 3GS have any advice?