Beyond the box

I had an iPhone battery replacement done at Beyond the Box in Vmall. They inspected the phone, and the only issue noted was swirl marks around the camera. After an hour, they called me to inform me that, after opening the phone and replacing the battery, green lines appeared on the screen— eh wala namang green lines yun nung binigay ko sakanila and never pa na oopen yung phone ko. What should i do?