MIgrate to SSD: Cannot boot with any bios option

I cloned my 1tb Windows 10 SSD to a 256gb ssd (only 200 gig of data) using Paragon Hard disk manager 15 paid version.
I booted into the 256gig clone once, but now i cannot boot back into my normal 1tb drive, i can only boot into the 256gb clone.
I unplugged the clone but no matter what bios option i chose, i just get "please insert valid boot media".

So now i am trying to clone the clone, back onto the 1tb, but still the same thing. I have reset by bios back to defaults but something has gone wrong.
What can i do? I've used paragon for years to create clones and this is the first time i've ever had a booting failure.

Please help.