[lubuntu] wont boot after install

im trying to install lubuntu on an old laptop
i set the partitions
/
swap
/home
and after install the bios not detecting the OS
its not UEFI because it does not support it i set the drive to mbr
what am i doing wrong?

i also tried the boot-repair it keeps showing me that its not a live usb
and i cant try it from ubuntu because the system gets stuck on this os