LCD not turning on after digitizer replacement.

My brother got an Ipad 6th generation A1893 for school

because of remote learning. He ended up cracking the screen pretty bad i i just replaced the glass. before taking off the LCD the ipad was dead, but when i pressed and held the power button the dead battery icon showed. took off the digitizer and replaced it and put back the LCD and nothing is coming up now. not even the dead battery icon, had it on the charger for 20

minutes and still nothing. tried pressing and holding the power button for 1 minute and nope. really stuck because my parents don’t want to pay $300 to get it fixed/replaced. double checked and all the cables and connectors are in right . nothing is broken or damaged.