Lights work.Battery has been tested. Starter relays have been switched around. Fuses are good. Get full power at crank fuse when turning the key to start. You can feel the starter relay click when attemting to crank when in PN but no click when in RD12 so i assume the nuteral safety switch is good. The battery cables have been cleaned… One thing i notice, turn key on the guages kick on, then turn it to start and they go back to the off position. When returned to run, the guages go back to where they belong. This is not my car dont know if this is normal. The security light does not blink just come on wait 5 seconds then go out. What else could it be
When those symptoms happened to my Silverado, a new starter motor fixed it. Try hitting the starter with a soft-faced dead-blow hammer to see if the bendix is hung up… Some parts stores have a starter tester in the store, but I think you have to take the starter off to get it tested.
I’m wondering how the battery was tested - though a whack to the starter is a fine place to start.
With your multi-meter set to volts and with a friend holding the cables from the multi-meter on the battery terminals (we won’t get into cables or terminals yet) see if the battery stays above 11.00 volts or so when the key is turned to start. The rule here is procede with your diagnosis with the idea in mind that all electrical system diagnosis starts with the battery.