Wicker, Apkano is absolutely on the right track. Your RCM lives in the electronics box on the passengers side of the car.
The next time this happens try taking the flat of your hand & give the box a decent whack. If it magically starts again then

it's the RCM probably failing.

If it still doesn't start, pop the cover off of the box & reseat all the cards within. Give the connectors attached to the boards a wiggle just to make sure they're seated correctly. If the car starts then

it's the RCM probably failing.