Swift is a week old and doesn’t start

Tomorrow I have a new Suzuki Swift 1,3 club since last week and already two times he did not want to start. The first time (last week Saturday) I got to hear that I should turn off the light, then the battery lasts longer. I let it be placed that you can not leave a lich without not getting deaf. Battery was only charged in the workshop and I got the car back. Yesterday the second time: car does not jump on. Then I bridged the Swift and then I am too Suzuki drove, but not where I bought it. They thought it could be the battery that might not have been properly maintained. Oh yes, after the bridge, the car jumped on again without any problems. Do you have any ideas what that can be? Will bring the little one back to the workshop tomorrow and wait and see what I can hear there. But other opinions are also not bad. Greetings