Look at your form 1040 ... which box is marked for the child ?   

Did you indicate the child was being claimed by the other parent ? 

I did accidentally click “credit for other dependents” I tried to amend it but turbo tax just keeps saying she doesn’t qualify but doesn’t tell me why she doesn’t qualify for the child tax credit. 
there isn’t another parent who could’ve claimed her. 

go back through all the questions for the dependent. make sure that the question did (dependent's first name) pay more than 1/2 their living expenses is answered "no"

don't know what version you're using but if other than the free version contact support if you can get the CTC to work 

Contact Customer Service
5am-5pm Pacific Time (8-8 Eastern) Monday - Friday
https://support.turbotax.intuit.com/contact

the other thing you can try is to delete the worksheet for the dependent then go back and re-enter. carefully read each question. also visit the CTC section