Replaced my screen and the light sensor everything went well but screen comes on and goes off and the. Powers off then back on. When a call or message comes in screen won’t come on but will hear the notification sound what do I do

deffently got to apply heat to that front screen due to the adessive bewhind or mostlikly crack the screen

Where can I get a good used motherboard for a A1954 iPad 6 gen everywhere I look, there sold out ?...