Toyota Rav4 2010 Model had a weird incident, and till now I don't know why

So yesterday, my car suddenly stopped working. Like when I try inserting my key and twisting it to try turning it on. Only the LED lit up. Basically, all the warning sign shows like dead battery, oil change, etc. But I wasn’t able to hear a slight engine noise. So I open the front and when I asked a friend to turn it on. I hear a very faint krrrrrrr noise. We all came to the conclusion that it was the starter. It can’t be my alternator because I had that replace 1 month ago. And it can’t be my battery because last time I asked Canadian tire to diagnose it, they told me I still have a decent amount. So unfortunately I had to call a tow. The day after that incident, I called in a mechanic to check out the car. Surprisingly, the moment he turn on the car I can hear the engine a little more. It didn’t fully turn on the car. He tried again and it worked for some reason. He doesn’t know the actual cause, but this was his guess. And I wanted to know if this true.

So he told me, a reason why it wouldn’t fully start the car is because your security LED could still be blinking. If you insert your key and that LED still blinks, then it won’t work. Now I was very very confuse. Because I use the same key, and he was using the same key too. So how come yesterday didn’t work. Now I’m just worry if the cause was my starter being overwhelm. Any comments would help. Because I really don’t want to spend money again on a tow truck. Thank you!

I presume you don’t hear the normal rrr rrr rrr sound with the key in “start”. That is called a “no-crank” or “fails to crank” in mechanic-lingo. The first test – beyond the obvious of making sure the transmission is in P or N and the battery is fully charged – is for your shop to measure the voltage at both starter motor input terminals. Both should measure at least 10.5 volts with key in “start”. What do they measure on your car?

If your key assembly contains any batteries, that could be the problem too.

Even though it was tested, how old is your battery?

Has anyone made sure all of the battery connections are tight and clean? After 13 years, those could easily be corroded.