DS Lite showing no image, Pluging it in turns on the light for one sec

Hi there, i have 2 DS Lite and wanted to place the working motherboard of one of them into the working shell of the other. I followed the iFixit tutorial, reassembled everything and testes, the DS turned on but the bottom screen was all white.

So i disassembled again, resetted the ribbon cable of the bottom one, then retried, only now it just dosen't do anything, and pluging it in just turns on the orange light for one second and nothing else...

any suggestion ? everything should be plugged in correctely, can send pictures

Also, i let it sit during the night, when i tried pluggin it in it worked… but the bottom screen was flickering white, so i resetted the ribbon again…. back to the won’t turn on problem…