Hello Charles,
I am very new to 3D printing so I am certainly a beginner but I would think you should be able to pull the filament out if you heat up the print core. I know you said it did not work cold nor hot. But I think you should try again by heating the core. Maybe by setting the temperature VERY high it should work.
You can achieve this (as you probably know) by going in the printer's menu.
(English is not my native language so I hope you understand what I meant)
Ronald