This may help . Always turn the iPhone 5s off before plug and unplug screen . If you want to test the screen before install it , plug the home button flex before switching it on . If your iPhone behave abnormal , unplug the battery connector and reconnect then switch the phone on . Good luck . Some iPhone 5s screen manufactured cause iPhone screen to go blank so make sure the second screen is not from the same manufacturer usually identified by the stamp it sticker with initials .
Sam
mpr-oxon.co.uk