Debian only boots when USB is attached? please help me fix it

I had some problems with my wdmycloud so formatted the harddrive and tried installing debian from the tutorial here http://fox-exe.ru/WDMyCloud/WDMyCloud-Gen2/Debian/ it’s kind of worked but it only boots into debian if the recovery USB is inserted

I checked for a boot partition using “lsblk” which lists the partitions but doesn’t have any marked with boot

root@wdmc:/boot# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 3.7T 0 disk
|-sda1 8:1 0 953M 0 part [SWAP]
|-sda2 8:2 0 3.7T 0 part /home
|-sda3 8:3 0 2.8G 0 part /
`-sda4 8:4 0 512B 0 part

does anyone know how to setup the boot partition?