High Sierra Question

Dear fellow ehMacian's: Maybe you can help me. I've been trying to install High Sierra on my Mac Pro (MacPro 5,1, which I think is from 2010-2011 so it's compatible with High Sierra, I believe). I've had a bear of a time trying to get this to install. I've tried the usual: zapping pram, resetting SMC/PMU, Ejecting hard drive #2, trying to start up in Single User Mode. I've also run Disk Utility on both hard drives and it's found no problems at all. I've checked the firmware and the Boot rom versions and both are current as can be. As far as I know, High Sierra checks to make sure you have the correct firmware before installing and you can't get around that. So, I've done what it told me to do from the High Sierra installer. Clicked on the Shut Down button....waited for it to shut down then held down the power button until I see the blinking power light and the long tone, then released the power button....and....
nothing.....absolutely nothing but a blank screen....I hear a little hard drive noise which indicates to me that something's going on...but as to what i can't say....:confused:
I've tried time and time again to get this darn thing to install with no luck. I don't get it....
it's not like I need to install it, my Mac Pro works fine as is, but...it would be nice to have that choice..... I'd rant and rave at Apple, but why bother? won't do me a lot of good...but seriiously?...Guess I'm going to have to wait for a bug fix for this OS install, which is the 1st time I've ever said that....
well? any insight appreciated
thanks

John B

via ehMac.ca http://ift.tt/2xSMDbi