Why does my laptop keep restarting after I installed a new ssd?

Hi,

Can you get into BIOS by tapping the F2 key several times just after startup?

Check if the SSD appears in the Boot priority order menu section of BIOS.

Also with some Samsung laptops if you wish to boot with a USB you need to disable "Fast BIOS mode" in BIOS > Advanced because if it is enabled it doesn't check the USB port on startup. It skips over it. Apologies if you knew this already.