Chosen Solution
Seemed to go ok but when I turn the phone one, the display comes up with the apple logo for 3s then goes black for 3s, then comes back for 3s, then goes black and repeats a few times until it powers off. What does this mean?
You need to determine if this is a problem related to your replacement screen or if some accidental damage was caused to the logic board. If the original screen was still functional, albeit cracked, try- re-installing to see if the phone works properly. If it does, then you may have a defective or damaged replacement screen. If the original screen also hase the issue, then closely inspect your logic board, connectors and flexes to see if there is any damage.
