Some suggestions:
start.sh
there is a cdk_new repo with need to be cloned
Why start.sh don't do that by checking existence?
Maby after that to suggest opening of make.sh from cdk or cdk_new
make.sh
when all choises are made is it possible to be written as file and next time make.sh was run,
to come message "do you want to use last choice settings" with printed selections
(box |kernel |image type |etc.)
flash.sh
is it possible to be added tvheadend version in filename
atevio7500_tvheadend_USB_CDK-rev1019.tar.gz
to
atevio7500_tvheadend-4.1-2347_USB_CDK-rev1019.tar.gz