update:
tried to unpack my modified .iso and check a bunch of text files contained
inside squashfs file - they are readable and seem to be as they should be
tried to make boot flash drive from modified .iso with rufus and hen replace
flash drive's contents (except squashfs file) with contents of another boot
flash drive made in the same way except from original trisquel 8 .iso file.
it shows boot menu but when "try trisquel without installing" is chosen it
shows this error:
Invalid or corrupt kernel image.
apparently only some parts of modified .iso got mangled (possibly written
with incorrect encoding, see above discussion)
how can I find out what parts got mangled?
