Nofia,
In my limited experience with mothers of babies refusing the breast and
attepted relactation, including my own personal experience with my first
child, even trying "a few times" to put baby to the breast with baby
pushing away or crying,  can cause negative associations for the baby.
If the baby really is refusing every attempt to bf, it may be more
effective to stop trying for a while...a few days, a week or more..
meanwhile pumping (even if there's not much there) and feeding baby with
cup, tube or even bottle (if this is the least stressful for the
mother). I've found both from my experience and from the experience of a
few other mothers, that giving the baby a chance to "forget" the
negative association with the breast for a while will sometimes do the
trick.  Then, when baby eventually does latch on willingly, the mother
can sit for hours on end and nurse, possibly use the SNS, and build up
her supply. I think it's important to consider the stress level involved
for the mother and the baby.  Trying too hard may backfire.
Good luck!
Yael Wyshogrod
Rehovot, Israel