After display change, Icloud Activation locked

Hi, I was using iPhone 5A1428 for a while, one day I restore my iPhone and forget password. Any how I unlock it using two factor authentication. Unfortunately my screen was broken, I order from iFixit and changed the screen successfully. But now the problem is I was unable to unlock icloud Activation, even though I know my Apple ID and password. I check my iCloud account, “Find my iPhone” is disabled. I didn't find any device under “Devices” in my account page. What would be the cause, Please guide me to unlock my phone to use as new iPhone.