Hello,
I have downloaded SPP201409 and created a USB stick with HPUSBKEY tool v1.8 that came with the kit. It will boot and display whether I want Automatic or Interactive and then display the HP logo whilst its loading and then it says Unbale to mount filesystem and give me the # prompt. Please see attached scrrenshot. I tried it on DL380pG8 and DL580G7 with same results.