problem with ssd, i don't know what to do

[tranquil sapphire]

I got gifted an old HP EliteDesk 800 G1 USDT (4GB RAM DDR3, Intel i5 4th gen, HDD).

I purchased a Lexar 256GB SSD.
Yesterday I tried to clone the current HDD with Macrium Reflect but the process stopped at 90%, so I thought the current hard disk is probably faulty.

I created a Windows USB Flash Drive so I can do a clean flash, the problem is that when i swap the HDD with the SSD the PC just has a black screen and nothing works, it doesn't enter the BIOS or other things. Just a black screen, it seems like it doesn't even go past the POST phase, it just turns on.

The new SSD is not, atleast it shouldn't be, faulty, since it's new from amazon and if i connect it with sata adaptor works normally.

And yes, if I reinstall the HDD everything works normally. It boots the USB Flash Drive, the OS, everything.

Any help is appreciated, thanks!

[arctic valve]

Reset the CMOS by removing the battery. This is one of the most effective ways to deal with old hardware.