Then remove bath and throw it away due to many scratches in the surface from tile dust (even if you cover it well first!). While your doing this you may want to remove the damaged tiles where angle grinder has slipped/grabbed and retile as necessary! Plus if you ever need a new screen you will be stuck trying to find one of the same, or similar, dimension for the wall channel.
DON'T use an angle grinder to do this. As we haven't seen your tiles it is difficult to visualise the problem, but surely the ridges cannot be that deep, use silicon as suggested after you have drilled the fixing holes and are happy with the position. If necessary don't use the manufacturers fixing holes drill your own to coincide with the tops of the ridges.
HTH
John