Sure it could be the crank sensor, but without spark it could also be the coil, the distributor cap or the rotor as well.
BTW, the PCM is dead center of the firewall above the engine. It's a silver box with three large connectors plugged into it.
Resetting the PCM is done simply by disconnecting the battery for 10 minutes.
The alarm could still be the problem. Some alarms use the normally open contacts on a relay to enable the ignition. So by disabling the alarm, the relay will never energize and the ignition will never power up. Some alarm manufacturers do it this way to prevent someone from pulling a fuse to disable the alarm and driving the vehicle off.