Hi @kendal34. Is this the same phone as the Touch ID - Home Button issue?
Open the phone and visually inspect all the connectors for the Screen assembly. Remember to disconnect the battery first.
iPhone 6 Display Assembly Replacement
The impact could have caused one of the connectors, specifically either the battery or LCD, to have no or poor contact. Look inside to see any other signs of damage. Re-seat all the connectors and try again. If you have access to a known-good battery and screen, you could also try those but only one variable at a time.
A jarring impact can also break some tiny solder connections underneath critical IC's or even have passive components break off completely. If that is the case, you will need to find a repair shop that does micro-soldering repairs or do an OOW replacement with Apple.