After months & months of the line/flickering screen problems, to the point of going blind, I moved the brightness cursor full right, turned automatic brightness off, set the auto lock to ‘never’ & bless my soul, lines are gone! As bob is my witness. I left those settings in place for 24hrs & I’m using it as normal. This is an iPad mini 2. I can’t remeber how old it is but it’s been well used.