Dropping the device can cause cracks or dead pixels. You will have to remove the screen from the remaining hardware, and replace the screen. There is a guide on iFixit with clear instructions on how to replace your screen and fix these issues. You may find more information on the HP Split x2 troubleshooting page.

The wireless issues could be caused by various issues. The Wi-Fi card may not be seated in the miniPCI Slot. You may have to download the driver for your Wi-Fi card. You may have to enter a password to access the wireless network. You may find more information on the HP Split x2 troubleshooting page.