Asus X515KA not booting. after flashing bios sometimes i come there. but then dead again

[tranquility]

hallo,

i have an asus X515KA-EJ058W here.
just both leds white...he battery blinking without battery connected

consuming ~400mA and tries to start but nothing happens but fan spinning if cpu gets warm
if i hold the power button it shuts down and consumes ~30mA i cant spot anything getting warm with thermal....the ec/sio a liiiitle but this is maybe normal beacause it is working ?
power on again is possible but again 400mA then and no picture.

now the really strange
i flashed bios (some version i found on the internet) and resoldered....sometimes it starts then

the first time i came to windows....restarted and dead again....i tried around maybe new flashed...then without ssd
sometimes i get to bios....most of the time its completely dead as told above..

what the hell is going on there ?

if i read the bios again after it was in the board...there are changes in the bin.
i think this is normal ? because as it tries to start it writes something to the bios which it has detected ? components or sth ?

can the bios chip nevertheless be faulty ?

or is it maybe the EC/SIO ? it has a rare name.... nuvoton NPCE68AAA0BX
and it might be necessary to program it ?

also i tried another RAM. but i am not sure if it is really compatible

i hope you understand my bad english and maybe sbd has an idea

[tranquility]

theres no obvious short when taking the 400mA. only cpu gets warm...seems to work and get warm....but no picture etc.

[tranquility]

if i re-extract the bios after flashing....i cont aopen then in uefitool !
the same with the original i extracted before i begin flashing the first time

so something seems to corrupt that bios again and again and again....but....i had a time, i could restart and restart and came everytime to the bios....strange