what poster? maybe my game is bugged? its just the feeder, binding tentacles, bed, and intercom
About poster.
When you use «try to escape» option several times, eventually you will find weak spot in the wall. If you have trained enough times, you can create a hole in it (again, over several days), which will be then covered by poster when not used.
About Abathur’s… problem.
Since a)hole and poster is among things Abathur comments about, and b)so far people who stuck here universally have not this poster on the wall, maybe we are not supposed to reach Abathur scenes before breaking the wall, and this is a bug? I wouldn’t eve be surprised. Can’t test it myself, all my saves are after breaking the wall (actually, I started game with it), and I am not ready to start all over again.
Either way, feeder is supposed to be checked after everything else is checked. Since alternative is restart, try check it again (if you only do it once), it can’t possibly become worse than that.
Sorry for broken English. Hope at least something becomes clearer.