Acer CB315-4H (Magma) doesn't boot after Full UEFI flashing

have several Acer Cromebook 315 (CBH-4H-P01E). two flashed last week - without issues. yesterday flashed one - it doesn’t boot anymore. today tryed flashing one more - same result, process went without errors but doesn’t boot anymore too

just flashed here on MAGLIA and no issues. MAGLIA and MAGMA both use MAGOLOR board/image, just different name string. So the firmware isn’t broken

edit: I did find some issues post flashing, so have rolled back the JSL boards to the 2405 release