does the lenovo flex 5 support the full uefi rom you get from mrchromebox firmware utility?
there’s a supported devices list on my website for a reason, why wouldn’t you check that first?
at the time i was having trouble identifying exactly what the model was the ebay listing listed it as lenovo ip and i didnt know ip stood for ideapad so i couldnt find it on your website its resolved now tho
did you look at the link on my site though? make/model are not always deterministic.
also, buying a Chromebook to run Linux isn’t usually the best idea