Chosen Solution
I replace battery, Power button is not working after the replacement. I cant put Ipad to sleet or wake using the Power button or I can not shut down Ipad using the Power button. Everything else seems to be working fine.
Do the volume buttons work? If not then you either ripped or forgot to reconnect power/volume flex cable.
maybe you have damaged the power button flat during the replacement i suggest to replace it it’s not that expensive
