Next time. Look for that little LCD window. If it's there and there is a Green check mark... It's GOOD.
You certainly don't want to keep turning on a battery device that sits for long periods of time and you want the battery to FULLY function in time of need.
I work at an ambulance company. We always get "newbies" that want to test the AED. They have to be reminded that they're literally wasting battery power.