Maybe put the broken parts back on to see if it works again
Go over your work to makes sure everything's connected , maybe you loosened something while inside the phone.
My mother dropped her HTC Desire 816 and it may have been ran over by a car. Now the screen and LCD are broken. The digitizer was fine. She ordered a new screen and LCD for it and I volunteered to fix it. Replacing the screen and LCD was super easy. However, now I can't get the phone to charge or come on. I followed the steps completely but when I plug the phone in for charging, all that appears on the screen is a battery symbol and the orange light flashes in the top left corner. What could I have done wrong? I would love to just take it to a repair shop but I literally have no money. How can I fix this? Could it be a problem with the battery or the motherboard?