Helppp.. My 09 chevy traverse won’t start

I have a 09 chevy traverse. It won’t start I
have tried everything! I took it to a mechanic
shop they couldn’t figure it out, so I had it
towed to bud clary they told me it could be a
fuel pump so they changed and it still won’t
start. Now they want to charge me more to
tear into the car... they had it for 3 days and
still don’t know what’s wrong with it.
Sometimes it will start but than die right away
no  Engine light.. No codes come up!