Lost hard disk after using Acronis to clone it

I am not using the computer that I have a problem with. I bought a new WD Blue SSD for my HP Pavilion All-in-one 27 - xa0009. This morning I downloaded Acronis and cloned the hard. I decided I did not have the expertise to carry out such a task on a All in one.
I the reconnected all the wiring and pressed the on off switch and I got the message that BOOT DEVICE NOT FOUND AND TO REINSTALL THE OPERATING SYSTEM The error message is Start PXE over IPv6 on MAC: 80-E8-2C-28-74.
Sorry about big letters, did not intend to do, I’m 83 and not too good with computers,
Any help will be really appreciated,

Sounds like you didn’t get the hard drive fully reconnected when you put it back in or a connection to it is loose.

Sorry, but I did not remove anything. I did not change nothing and I did not open the computer. All I did was clone the disk and shut down. When I installed all the wiring nothing functioned.

Still sounds as if you disconnected SOMETHING and did not RE-CONNECT it properly. Maybe I’m misunderstanding due to language barrier…

Just to be clear, what do you mean by that original part of your post? Which wiring did you reconnect?

Also do you still have the new SSD drive connected to your HP? If so can you unplug it and try and reboot the computer, in case it’s trying to boot off the SSD drive and failing.

I did open the computer I looked at how it could be done and I chickened Out


Next step then would be open it again and double-check everything is securely connected to the original drive inside.

Also be sure that the new blank drive is not connected, so there’s no chance the machine is trying to use it to boot up.