Won’t boot from m.2

[Benny144]

ive installed a Samsung m.2 drive on my PC, and cloned my old SSD to it.
Every time I try and boot from the m.2 it tells me to insert a valid boot drive and press any key.
What could I have done wrong? What else Can I Check?
Thanks in advance

 

[Armageus]

What software did you use to clone it?

Presumably Windows 10?