lcd not working after touch replacement

Hello, so basically i replaced a touch screen on an ipad mini one and after there were lot of lines in lcd. i thought i have broken the lcd and changed a new one but there is no display on new lcd. i have changed 2 new lcds but no dispay on both ofthem but if i put the original lcd back display comes on with lines. apparenly there is no crack on original lcd. So what should i do.