[almost] big problems rpi4

hey guys,

i just received my new rpi4, installed a fresh libreelec + hyperion (same setup has rpi3)
and it just doesn't work :
1- i have to switch off led power suplly before i start rpi, if i let ON the rpi doesn't start (no display)
2- ssh connection is ok and install seem ok but nothing happen no rainbow.
3- if i try to take a screenshot from hyperion i get error: no picture found check ssh ......
4- i can press start / stop from hyperion nothing happen

unplugged my rpi4 and replug my rpi3 : all is ok

wow i couldn't imagine having so many problems with this new raspberry, very disapointed

any idea why i have so many problems? i presume a hardware configuration?
ps : latest libreelec installed (LibreELEC-RPi4.arm-9.1.502)

well, at least it's "working", leds are alive

1- I removed my level shifter, uninstall hyerion and remade wires + reinstall app
2- maybe i didn't wait for "send config" in hyperion? i waited 1-2 min , and when I clic "start" : i saw rainbow :LOL:

3- i still have my power issue, if I let ON my led power supply before starting my raspberry it doesn't start. If I switch OFF led , start the Rpi and switch ON : it seem "ok"