Display Screen Not Working

Replaced battery, Then replaced screen. Phone will not vibrate when turned on or display charging icon when plugged into charger. The disassembly and reassembly went fine. No damage noted during disassembly/reassembly.

Battery showed an initial charge of 3.82 V, 4.32 V after charging.

Ruling out a defective new screen, what are the most common hiccups?

Thanks for any input.