I've seen the other questions, but almost all of them deal with manipulating quantum states so that the other person reads a message in the data. However, you cannot force a quantum state on something without breaking entanglement.
So here is my idea. I know that it can't work, but I don't know why. If someone could point out the flaw, I would appreciate it. I do not claim to be an expert.
So there is the double slit experiment. If I pass a single photon through a double slit, it will create an interference pattern. This is the evidence that it is in a quantum state because a single particle should not be interfering with itself. In reading article above, this also works my photon happens to be entangled with another photon.
Now in the quantum eraser section of the linked article above, it goes on to mention that if you apply a filter to one of the photons (i.e. measure it), than the interference pattern of both collapses. Thus, by measuring the quantum state of one, both collapse.
So, here is how I propose FTL communication.
Lets say I create streams of quantum entangled photons. I will split up the pairs of quantum entangled photons and send one half to $A$ and the other half to $B$ in order. Thus, the first photon that $A$ receives will be entangled with the first photon that $B$ receives.
At $B$'s end, each photon will be run through the double slit to detect whether an interference pattern exists. If there was an interference pattern, then this is encoded as a binary $0$. If there isn't an interference pattern, then this is a $1$. It doesn't matter which slit the photon is known to travel through - the simple absence of the interference pattern is enough.
At $A$'s end, to communicate, I will encode my message in binary and then encode each bit in photon stream. If the next bit is a $1$, I will measure the next photon, thus collapsing its quantum state and eliminating the interference pattern. If the next bit is a $0$, I will not measure the next photon.
$A$ needs to send 1101. $A$ would measure the first, second, and forth photons. At $B$'s end, when these photons are run through the double slit, you would see that the first, second, and forth have no interference pattern, so you would know they are $1$s. The third retains an interference pattern, so it would be a $0$.
This allows $A$ to communicate to $B$ instantly. For $B$ to communicate back, you could create another set of streams where $A$ runs the photons through the double slit and $B$ measures to collapse the quantum state on some photons. Alternatively, odd numbered photons can be used for the reverse communication, so long as both $A$ and $B$ agree.
So, what is wrong with this method? It does not try to force a photon to go through a slit, but rather uses the act of observing or measuring to collapse the quantum state.