Linux Mint 19.1 is not been recognised after successfully installed on SSD in Caddy in place of DVD driver

[Guend1]

+ Linux Mint 19.1 is installed successfully on a SSD in Caddy in place of DVD driver, on a Laptop Toshiba Satellite C650

+ But after installing, Linux Mint 19.1 is not been recognised.
+ This SSD itself with the same Linux Mint 19.1, works fine when connecting it externally through an Enclosure USB.
+ The SSD itself is able to be written or read files easily through the Caddy
+ I tried with two Caddies, with the same result.
+ I tried also two SSDs, with the same result.
Any help is very appreciated

 

[Jeremyb]

Can you change BIOS boot menu settings, see what options are there?

 

[Guend1]

@Jeremyb
Many thanks for reply
In The BIOS boot settings, through F12, the list doesn't include Mint!

 

[Jeremyb]

BIOS might still show optical drive even though a caddy is there

 

[Guend1]

@Jeremyb
Unfortunately it shows non