You may need to boot from a flash drive to be able to see both bootloaders.
1-Create a USB device with an installation image.
You can create using the media creation tool, download it on this link.
https://www.microsoft.com/en-us/software-downlo...
2-Enter on BIOS/UEFI and change to boot from the USB device.
3-On the installation screen click on "Repair your PC" in the left bottom
4-Click on "Troubleshoot" and then the Advanced Options page will appear.
5-Click on "Command Prompt".
6-Then check if you a able to see both bootloaders and set the SSD as the default.
If you are still not able to see both boot loaders, you will need to disconnect your HDD to see what is preventing the boot from the SSD.
To disconnect the HDD, you just need to "Release the zero insertion force (ZIF) connector (1) to which hard drive cable is connected, and then
disconnect the hard drive cable from the system board. ", you can see how to do it in page 35 of this manual.
https://h10032.www1.hp.com/ctg/Manual/c06001791...
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
After disconnecting the HDD, try to boot from the SSD and check which error message you will receive, take a photo and attach it here.
