I switched the EXT_CARD for INT_CARD in the bootmenu.d item file and Debian started right up.

I have a couple of issues/suggestions

Add the created user to the sudoers file during setup
Any chance of a keymap guide? (ie how do I do | or tab)
Ctrl+key shortcuts don't work in nano
Is there a way to make the Fn key on the N810 sticky?

Any chance of using the information here to boot the tablet quicker?