So the EKA allowed the doors to unlock, but you still get Engine Disabled? Do all the doors lock/unlock on the key in the door now? If so, try syncing the key fob in the door by pressing/holding lock whilst locking the vehicle with the key, and then doing the same with the unlock button whilst unlocking the vehicle with the key.
If the fob then locks/unlocks the doors then try starting it again. IF it doesn't, then maybe try entering the EKA again.
Regarding the diagnostics - there's a few reasons it might not connect. The BECM talks best to diagnostics with the ignition OFF. Also there could be corrosion in the OBD socket, stopping the diagnostics from connecting properly. Also there could be corrosion in the footwell connectors in the RHF footwell where the power from the fuse box to the socket runs through. I've also seen corrosion in the diagnostic wires in the dash loom where they splice to the different ECUs, but it is also worth checking the fuse in the underbonnet fuse box as there's one there for the diagnostic port, and if that's blown then you might not get communication either.