Messed up high Sierra update, please help!

[RitchN]

Hi, I’m a complete newbie to hackintosh builds and have seriously messed up updating my first sierra based build.
I decided to update to High Sierra, but didn’t follow the intstructions at all!
I started the updated from the Sierra os, without updating any of the setting within the efi partition or disabling the graphics driver.
So the install got most of the way through and then hung, back at the clover start up screen it now shows both the update and the exsisting os, but I can’t access the original Sierra os at all to change anything.
After lots of messing around, including changing the BIOS settings to work of the internal cpu graphics and removing the graphics card, I still can get it any further than a series of small vertical white lines running across the screen.
Does anyone have any suggestions, even if it’s going back to the Sierra os. If so how do I do a clean install? I have a external case for the m.2 ssd and an old Mac mini to reformat the ssd, but is that a practical option?
Any help at all greatly appreciated

 

[RitchN]

Whoops hit return by mistake

 

[RitchN]

Decided to remove the ssd and reformat externally, then just started back with a clean install to Sierra from usb. Followed the same guide as last time And all is OK, only issue is that it recognises the graphics card is system profile, but isn’t shown in the initial about mac start page as graphics. Any help on this appreciated.