HP Compaq Pro 6300 MT - not booting followed by HIGH fans

[TeacherGuy2011]

Here is the problem we are having on 5 @ HP Compaq Pro 6300 Microtower systems:

https://flipgrid.com/314f70c9

Switching out PSU,  checking RAM,  replacing CMOS batteries............ can't get the systems to boot.

[WAWood]

@TeacherGuy2011 

From the video, it looks like the screen remains black all the time -- is that the case?

If so, you should try pressing F10 repeatedly during reboot to get into the BIOS settings.  Once there, go through the settings for boot options and see if you have them set so the detail messages do not display on the screen.  IF so, change the settings to see the detail POST messages -- and reboot.

IF that works, at least you will see something on the screen that might provide clues as to how far into POST it is getting before it stops.