I understand your system POSTs but crashes during operating system boot process.
It would help sharing the operating system version and exact verbatim of the error message.
When you tried to boot from other SDD/HDDs, was the operating system already installed or are you trying to install it?
Just a suggestion on something to check: O/S boot failures can be caused by an incompatible Chipset SATA Mode. For example, installing the O/S with the mode set to AHCI and then trying to boot it with the mode set to IDE (or vice versa).
thank you so much for the help. You are my hero today! I really thought buying a new system to be able to work today - but you saved my day! Thank you!
No problem; always glad to help...S