Issues with iFixit support

Just got the new battery replacement for a late 2014 model a d I am having an issue with a black screen and I have done everything I can possibly think to correct the issue. Resetting the Ram, configuring the battery for optimal use. Plus a new dispute ribbon into the computer and still nothing the battery works and so does the computer. I am using an external display and the computer is completely functional except fo the built in display which won’t turn on. Also back light is not on. So any thoughts. I tried to connect with a respective at iFixit and I have to say very disappointed with the gentleman I talked with. Not helpful at all and just stated I should return the item for a refund or request a new battery.