Car not start, dash flicker, then leave key in on position for time, and car work.
 

My 2010 Camry 3.5 v6 has been experiencing intermittent issues. While driving the check engine light will come on sometimes. Sometimes when I go to unlock the car with the keypad it barely makes a noise, then I get in the car and try to start it and the car just makes a click and all the dash lights flicker and the car wont start. I turn the key to the on position the lights will continue to flicker then eventually after some time the lights will come on and then the car will start. This doesn't happen all the time. But it has been going on for the last 3 months. I have checked the alternator and connectors and battery please help

Try to narrow down if the issue is the ign system that activates starter solenoid or battery that powers the starter motor.

When the problem happens, apply 12v to the ign side of the starter solenoid to determine if he engine now turns over.

If OK try to apply 12v directly from the battery to the starter motor terminal to power the starter directly.

Check the high power fuse links for corrosion.