2X LLOS 5 install failure

[Şerban S.]

[...]The boot loader was on partition /.  This was on an external USB HDD that had EXT4 partitions set up for this. [...]

1. You are using an external device. Without a thorough experience, this is what happens. You need to read a lot about the boot process, before playing with bootloaders, external drives and multiboot.
2. Reinstall Linux Lite and when you reach the Partition Manager, choose "Something else".
3. Look very carefully at the bottom of the screen, where is a combobox, and change the intallation place for bootloader, to /dev/sdb. Never use a partition (you used /dev/sda1) to load the OS when you are aiming multiboot. The bootloader has to be at the beginning of the disk, first sector, when you use MSDOS partitioning.

Good luck!