You can create a new bootable Windows 8.1 USB drive.
You can renable Secureboot and UEFI, as the Windows 8.1 and Windows 10 bootable USB do support UEFI.
https://www.microsoft.com/en-us/software-download/windows8
Try to reinstall windows 8.1 first.
Then go to support.dell.com, put in your service tag, and make sure you have the latest Windows drivers and BIOS.
Then go ahead and download Windows 10 and make a bootable USB.
https://www.microsoft.com/software-download/windows10
Run the SETUP from within Windows 8.1
Becareful at what you choose, it may wipe your hard drive. Before doing any new installs, you may want to back up your files. You will have to remove the hard drive and connect it to another computer via USB enclosure.
Here is a video on disassembly to remove the hard drive.
https://www.youtube.com/watch?v=CNuG3FLhH3Q