yes, you can open it up, put it in usb-disk mode, and do what you will.
[ https://github.com/monome/norns-image/blob/master/readme-usbdisk.md ]
(NB: the newest boards look a little different from the photo, the power-mode switch is much bigger and easier to use.)
i’m not sure what your “blank slate” looks like. if it’s a linux box with nothing on it, then at the least you will want the kernel build and overlays to make the built-in soundcard work - these are in every update tarball. if you want supercollider, you can either build it yourself or use debian and install the .debs that are also in the tarball. if you want the norns lua / menu stuff, yep, those are in the tarball too, so i’d just run the update script on a vanilla rpi debian. (i’m like 85% sure that would give you a working system.)
we don’t regularly build and post “factory images” simply because this would take up a lot of time and bandwidth, it’s rarely useful and is a relative PITA to apply.
in short, i wouldn’t particularly recommend re-flashing the whole filesystem unless something has been inflicted on it to make it unbootable, or you want to do something with the norns that is totally different from what we’re doing.
i can’t reproduce this. maybe post more details?
it is possible to put the output at an inaudibly low level (say -60db) and then put reverb output or compressor makeup gain at a correspondingly very high level, such that the output is inaudible with the fx disabled? 