While I am not familiar with the EFI you mention and have, I have heard of injector failure that would fill a cylinder with fuel and cause a lock up. This was a problem with early GM efi's, IIR. Can't compress a liquid. Do not confuse this with what you mention as a 'vapor' lock which is completely different as a vapor is a gas. In automotive speak, usually refers to fuel boiling in fuel line, hence, boiling liquid=vapor and creates a hard or non-start condition. Whether fuel or H2O caused, the result is the same, engine damage with an "S" shaped connect. rod. What came first, cyl. crack or liquid lock-up is debatable without inspection. Regardless, better to check it all out (components), and I do mean thoroughly check out ALL components including magnafluxing and Zyglo-ing and checking critical tolerances or you are bound to repeat history.