What IC chip are they talking about? I have seen IPhone 7 with the same symptoms caused by
· Baseband IC
· Baseband power management IC
· Tristar IC
· Tigris IC
· NAND IC
· Audio IC although the phone usually ends up booting after some time.
· Problems with the battery. Dock or gas gauge lines
If you need your data I would find out more about what IC they are going to replace and what diagnosis they did to come to this conclusion.
Just replacing random chips brings more variables into the repair which can result in a deal breaker.