In any event, try jumping the starter motor relay and see if the starter motor spins (if not it's a starter motor or starter motor circuit related fault). If it does start then try a new relay and if that does not change things try jumping the ignition relay as this will tell you if it is in the ignition/relay (try a new relay) smart shield circuits or the starter circuit or BCM. To jump the relay bridge pins 30 and 87 of the relay socket (transmission in park or if a manual trans in neutral and handbrake on with nobody standing in front of or behind the car and preferably someone in the divers seat with foot on the brake pedal- so no fatal accidents). Use a heavy gauge length of electrical cable with a suitable spade connector crimped on each end to jump the relay. If that's too hard and you want to make the investment you can also just buy switched relay bypass kits that do this for you with the convenience of a switch e.g. https://www.plusquip.com.au/product/eqp-109-relay-bypass-switch-master-kit/ or IPA 3pc Fuel Pump Relay Tester Bypass Kit #9036 | eBay or Thexton Relay Bypass Electrical System Tester Kit #927 | eBay etc You just swap the relay for the compatible bypass and press the switch on.
It might also be the transmission inhibitor switch so see if whacking the gear leaver in and out of park makes any difference.
Also check the fuel cut-off inertia switch in the kick panel / scuff plate on the passenger's side and next time try pressing the button for resetting this switch; see your owner's manual for more details. It's designed cut off the fuel in case of an accident (impact or rollover) and may have become faulty especially if water has ingress into that are an d corroded terminals so it make a bad connection so they sort of half turn off and/or become over sensitive as they some times do (if so a new switch is the answer). Also check the condition of the spade connectors on the starter motor they tend to corrode causing intermittent starting issues. Pull the terminals off after disconnecting the battery and give it a spray with contact cleaner lubricant and a scrub with a copper or brass wire brush e.g. https://www.repco.com.au/en/car-care-panel/panel-repair/wire-brushes-discs/josco-brush-kit-hand-3pce-bhb3b/p/A9778910?kwSearch=wire brush and Contact Cleaner Lubricant Spray Can | Jaycar Electronics or T3061A - Chemtools Contact Cleaning Lube Aerosol 175g - Altronics or https://www.repco.com.au/en/oils-fluids/degreasers-cleaners/other-cleaners/repco-contact-cleaner-aerosol-350g-racontclean/p/A9627134?kwSearch=contact cleaner or SCA Electrical Contact & Parts Cleaner 350g or WD-40 Specialist Automotive Contact Cleaner Spray -290g
It might also be the transmission inhibitor switch so see if whacking the gear leaver in and out of park makes any difference.
Also check the fuel cut-off inertia switch in the kick panel / scuff plate on the passenger's side and next time try pressing the button for resetting this switch; see your owner's manual for more details. It's designed cut off the fuel in case of an accident (impact or rollover) and may have become faulty especially if water has ingress into that are an d corroded terminals so it make a bad connection so they sort of half turn off and/or become over sensitive as they some times do (if so a new switch is the answer). Also check the condition of the spade connectors on the starter motor they tend to corrode causing intermittent starting issues. Pull the terminals off after disconnecting the battery and give it a spray with contact cleaner lubricant and a scrub with a copper or brass wire brush e.g. https://www.repco.com.au/en/car-care-panel/panel-repair/wire-brushes-discs/josco-brush-kit-hand-3pce-bhb3b/p/A9778910?kwSearch=wire brush and Contact Cleaner Lubricant Spray Can | Jaycar Electronics or T3061A - Chemtools Contact Cleaning Lube Aerosol 175g - Altronics or https://www.repco.com.au/en/oils-fluids/degreasers-cleaners/other-cleaners/repco-contact-cleaner-aerosol-350g-racontclean/p/A9627134?kwSearch=contact cleaner or SCA Electrical Contact & Parts Cleaner 350g or WD-40 Specialist Automotive Contact Cleaner Spray -290g
