can I rescue this botched up install?
What is wrong with turning off secure boot? It's a Microsoft gimmick to disqualify older hardware from running Windows 10 and everything after that. You don't need it.
I've never used it. There is absolutely no benefit, unless you go online without protection, which is like a 16-year-old white girl in a bikini and spiked heels, roaming the docks at 2:00am Sunday morning, screaming "I've got 3,000 dollars cash on me!"