iPad 9 won't boot a few weeks after digitizer replacement

I replaced the digitizer an an iPad 9 cellular, for some reason the next day it stopped responding to power/boot. Even when plugged in.

I put in a 2nd digitizer after I cracked the first replacement one trying to see if I forgot everything, made sure the battery screw etc were in properly. It worked for around 2 months and started rebooting, now it just doesn't power on at all.

I'm wondering what could the potential causes be, especially as it didn't respond to being plugged in.