Didnt unplug the battery connector while changing the display

I need help, my ipad display isnt working. I have an ipad mini 2, the display (not the digitizer) was partially destoryed with black pixels due to force but it was still working, its really roughly used and repaired. I only changed its digitizers a couple of times. Luckily, i already have another ipad mini 2 lying around which is completely destroyed but its LCD display is completely fine, so i opened the ipad and simply disconnected the LCD connector (its not broken) and i installed the other LCD from the other ipad. I powered it on, but i couldnt see any display, just a black screen. I tried to put the old LCD back, same results, no display. I then read an ifixit guide and it asked to disconnect the battery connector first before disconnecting the lcd connector. I didnt remove the battery on the ipad, should i remove it? Also its a really old ipad so apple doesnt repair them and i dont want to repair it because i have the parts.

I also cant power the ipad off, i put it away hoping the it would lose charge after a day or more.

Can i unplug the battery anyways and put the display back on hoping its backlight fuse isnt blown??

Also, i have changed the digitizer many times without disconnecting the battery and it was fine.