I did the same thing, but like I stated before, as soon as I rebooted it went right back to windows 8.1 as the default boot manager. The problem was not, that I couldn't boot Linux, the problem was I could not have linux as the default. if I pressed F9 at start up then I could choose whatever boot manager I wanted, but I had to press F9 at start to do it, otherwise windows 8.1 booted. many others smarter than me have had the same problem with HP Pavilion laptops with UEFI. Microsoft or HP have something hard coded in the system that always replaces the windows boot manager as the default if it is removed, name changed, or damaged. The only way I could get rid of it was to Erase the hard drive, make a new partition table using GPT and making a EFI partition for linux doing away with window 8.1 completely. I need windows for my tax program so will try to install windows 7 and dual boot with it instead of windows 8.1 I would not have this problem if I would use MBR instead of GPT and UEFI, but I am stuborn and want to use Uefi and GPT. I like the GPT partition table because you can have unlimited primary partitions and hard drives bigger than 2TB. I am going to experement some more with Windows 8.1 and see if I can find where the extra windows boot manager is stored and replace it with Linux boot manager changing the name and see if that works. Itried easy bcd and it borked my computer. ReFind works, but when I bootup it reverts back to Windows 8.1So, I used efibootmgr to set the WIndows bootloader as primary (so the repair techs wouldn't get 'confused' when booting my laptop) and this resulted in some problems restoring rEFInd after recieving my repaired machine back.
Using bcdedit from within Windows (administrative CLI) had no effect. I had to boot from a Mint USB drive, install efibootmgr, and set rEFInd as the primary bootloader (manually mounting the boot partition and using, in my case, sudo efibootmgr -o 0005).