Phone shows apple logo for 2 sec. then nothing. backlight stays lit

hi, so a customer brought in an iphone 6 plus that wouldn't turn on because it was ran over by a car.

after looking at the board under a microscope it didn't look bad so i decided to give it a shot.

when it 1st came in i hooked it to dc power and it booted just fine.

however it wouldn't boot when i tried with a known good battery.

also when i put it on charge and monitored it with a usb amp meter, i saw it would seemingly charge normal, then it would go to 0 amp and that's when the phone would reboot.

then it would seemingly charge normal again, but still wouldn't boot with the battery.

so i replaced tristar and nothing changed then i changed tigris as well.

still nothing.

but i left it on the charger and it kept bootlooping and i felt it getting really hot up by the cpu, and after another microscope inspection in that area found a cap that was visibly charred (c1228) , so i tested it and in diode just to be sure and yes it had a 0 voltage drop to ground on both sides.

so i replaced it with hot tweezers as to not disturb the cpu or pmic.

then tested again against known good board and it had the proper voltage drop to ground.

but now it wont boot at all even on dc power.

it does however continue to charge even after the apple logo cuts off. and the backlight stays lit.

i'm getting all the proper voltages when probing around tristar and tigris.

and when i try to update it doesn't go through because the phone does not stay powered on.

and according to 3u tools it's in recovery mode.

the only thing i can think of now is a nand issue but i was just trying to get some advice from the forums before i try anything else.