had the same problem , tried all the solutions on other sites
leave charger in overnight , hold down vol up and on button for 15 sec etc
nothing worked !!
took sim card out and sd card to use in my old phone , tried the next day ( not been on charge ) to turn it on and surprise surprise it did :-)
perhaps charger in ( no light was showing ) then taking the sim and sd out , then try turning on
worked on mine , good luck ….very very frustrating !!!