I would suggest that you create a SeaTools for DOS disk to check the HDD.
https://www.seagate.com/gb/en/support/downloads/seatools/seatools-dos-master/Pressing and holding F2 as you switch on will get you into the BIOS to change the Boot order.
If the machine uses an UEFI BIOS then you will need to disable Secure Boot, otherwise use the cursor keys to navigate to the Boot tab, use the cursor keys to select the CD/DVD drive then F5 or F6 to move it to the top.
Insert the disk - press F10 to Save and Exit then press enter.
You may be prompted to press any key to boot from CD/DVD.
There are short and long tests you can use - but really, we need more details as to how this came about as there could be other reasons as to why it won't boot.
