Hp laptop won't recognise iPhone 5s

Hi, I have an iPhone 5s that shows up as unable to recognise/ device has malfunctioned when plugged into laptop. Itunes won't recongnise either. It's fully updated and so is itunes. I've uninstalled drivers and itunes and reinstalled and still no luck. Ive spent an hour following various guides on the Internet which havent made any difference, mainly deleting and reinstalling drivers, iTunes and restarting computer. I can connect various other devices so know it's not the cable or USB ports. I've changed the charge port and no difference.The phone charges and works perfectly otherwise. I own a phone repair business but this has beaten me. The phone is still under repair warranty but was badly beaten up and I've fitted a new housing and screen and suspect apple won't touch it. Any help would be greatly appreciated.