Thanks rokytnji . I 've followed the information with all CD's . Checksum was always OK !
Symptoms are : vmlinux and initrd.gz take 1 second to load while 5.6 version takes 4 or 5 !
After message "Loading Kernel modules" a lot of errors coming to screen as no sync , abort ,kernel panic . As I said , 5.6 is quite enough for my needs , but if possible , I test to go ahead . Any problem with Kernel_architecture isn't adjusted with "Celeron M 1.5 processor" .
I tried to update using my 5.6_SFS ; the operation seem to be OK , but "panic kernel" is there , before terminate ! Next days I w'll find to test again and send the frustrate image of my screen .
Repeated thanks .