One needs several steps to get a Brother Scanner; if one uses the install script, it does seem to cover some or all of those steps; Brother provide an FAQ http://support.brother.com/g/s/id/linux/en/faq_scn.html?c=us_ot&lang=en&redirect=on and from that
1) sudo apt install libusb-0.1-4
..even if networked do this
http://support.brother.com/g/s/id/linux/en/faq_scn.html?c=us_ot&lang=en&redirect=on#f00107
2) http://support.brother.com/g/s/id/linux/en/faq_scn.html?c=us_ot&lang=en&redirect=on#f00101 copy files under /usr/lib64/ to /usr/lib/.As the MFC-J615W is a brscan3,
sudo cp /usr/lib64/libbrscandec3.so.1.0.0 /usr/lib
sudo cp /usr/lib64/sane/libsane-brother3.so.1.0.7 /usr/lib/sane
sudo cp /usr/lib64/sane/libsane-brother3.so.1 /usr/lib/sane
sudo cp /usr/lib64/sane/libsane-brother3.so /usr/lib/sane
sudo cp /usr/lib64/libbrscandec3.so /usr/lib
sudo cp /usr/lib64/libbrscandec3.so.1 /usr/lib
3) for a usb connection, one needs a udev rule; http://support.brother.com/g/s/id/linux/en/instruction_scn1c.html?c=us_ot&lang=en&redirect=on#u13.04 and you download a tiny file brother-udev-rule-type1-1.0.0-1.all.deb
4) for network config, Brother offer this http://support.brother.com/g/s/id/linux/en/instruction_scn1b.html?c=us_ot&lang=en&redirect=on
brsaneconfig3 -a name=(name your device) model=(model name) ip=xx.xx.xx.xx
They suggest to check it worked, do this
brsaneconfig3 -q | grep (name of your device)
Does any of this help?