Why is there no action from taptic engine after audio ic replacement?

So i recieved an iphone 7 that had the audio ic replaced. The customer said that it doesnt vibrate and people can not hear them as well as putting it on speaker changes nothing and sound still comes through the top speaker. I tested everything and they are correct about all of the issues. Also they stated that it will restart randomly for no reason. If any one could help me narrow down what's wrong with this board I would greatly appreciate it. Thank you all in advance!