chevy impala intermediate no start

Ok Mother-in-law brings her car over to Autozone because of CEL they got no codes.
So she comes to me and asks if I could get codes from a relay or the ignition switch I tell her no.
So she tells me her CEL is on they got no codes and sometimes it acts like it won't start.
I try to start the car a few times and I confirmed what she said So I tell her to let me put my scan tool (Autel ds708) on it to see what it tells me.
So I do and get no codes I go to start the car and it won't start and disconnects the scanner.

any ideas?? Thank you in advance

P.S I also started the car by turning the key to crank and immediately let the key go.
I forgot It's a 2008 Chevy Impala 3.5L

P.P.S I know about the recalls

I would do an "auto scan" with the ds708. instead of just the ecm. I have the same scanner. let us know what you get.

The car won't start if you hold it in crank vs a quick "snap" of the key? It cranks every time? At point of no start, what's missing (spark, fuel etc.)?

I did an auto scan and the only codes I got were for air bag and A/C .

When I went to start the car it would not start and shut down the scanner it should not do that I should be able to start the car with the scanner hooked up.

So on a crank the scan tool shuts off completely? If so, the ECM could losing power or ground causing a no start.

That's what I thought I'll check the ECM and see where that takes me

so when it doesn't "start" its a no crank? or A crank no start?? next time it happens id check for voltage on the s terminal of the starter with a test light. could just be a bad starter. if you have power put a starter in it.

I wanna thank everyone for their help But I'm no longer fixing this problem.

Again Thank you