Electrical fault issue -AA man stumped

[Beetledoggy]

Hi All. Yesterday morning the Grandland (2018) decided not to start. The motor turns over but nothing catches. Dash comes up with ‘automatic brake system fault’ , after trying again it said engine fault, then again back to the brake fault message.

Everything else works - central locking, lights etc. finally had to get AA who came and tried the usual diagnostics but no joy. Another AA man came and he tried all sorts but again no joy. We had to be towed home. AA man suggested we try the other key in case it was a key fault/immobiliser issue but again made no difference.

Any suggestions ? Typically we are 1 month outside the warranty and garage will no doubt charge £100s. Thanks