Hello, I hope the following assists you.
As the speedometer is showing dashes then there is a communication issue with the engine management control module (PCM), the immobiliser system is integral to this module which is why the vehicle remains immobilised. When the PCM won't communicate no diagnostic tester will be able to access the system.
You need to check the power and earth supplies to the PCM, the PCM is located just behind the driver's side front suspension strut top, you can see the connector if you look in this area in the engine bay it will have a metal security shield over it.
Before accessing the PCM check that the PCM relay operates, the relay is located in the engine bay fuse box, it is the left hand small relay of the 2 small relays in the middle of the fuse box. With the ignition on pins 2 and 5 should be a 12 volt feed, pin 1 is earthed by the PCM to operate the relay.
Check fuses 9, 33, 40, 41 and 42 in the fuse box under the bonnet plus fuse 67 in the fuse box inside the car as all these fuses supply the PCM and associated systems.
Check the main earth points in the engine bay, the earths under the battery and on the driver's inner wing near the PCM connector. You can try disconnecting the instrument cluster as there are problems where the cluster can shut the PCM down so disconnect this and see if the PATS light operates correctly.
It is a little unusual that the immobiliser light flashes fast when the PCM is not communicating, normally it continues to flash at the same rate as it does when the ignition is off.
Start with these points and let me know if I can advise further, I'll reply as soon as I'm able to.