@jwcph @cybervegan What an ordeal! I'm very happy you were able to fix your boot situation.

@jwcph So I'm guessing your Mac was using GPT partitioning and that I think used a small dedicated boot partition that essentially got overwritten in the dual booting. That's just how it has to work on some level.

I'm really just not sure about the current state, whether the old partition remains, or what tools exist to restore it. In theory you need a recovery usb that could restore or recreate the partition that would magically let you boot up, unless there's a way to do it with native tools that I haven't found. Unfortunately I know next to nothing about Macs and I haven't bothered with keeping up with recovery tools. Sorry I can't be of more help, but I hope you find the least painful option here.

@jwcph if you are going for the nuke option i think you want to look at method 3 here:

https://witechpedia.com/guide/how-to-install-macos/

I'm not sure of the end state desires regarding partitioning, so I'm not sure what's there and what to recommend (like if you're going to try dual booting again). But you should be able to get back to a bootable new install pretty easily.

@jwcph you mean when you get into internet recovery mode, then disk utility can't see that there is a disk when you use Show All Devices?