Black screen on startup

Try clear CMOs by reset jumper on motherboard.  You need to know how to access mobo safely by d/c power cord, draining all residual power by pressing power button for 15 sec, grounding fingers on chassis. Move blue jumper to adjacent empty 2 pins for 15 sec, move jumper back.

@DifferentSun   What color is the PC's power button and is it steady or blinking? If blinking, count the blinks which are an error code.

Try connecting a TV or external monitor to the HDMI-OUT port on rear of PC and then reboot.  That might help you pin down the source of the problem. And, if nothing else, might be a workaround to let you use the PC and then back up all your personal files asap...

I don't know if this would help but I have my cousin over and he said he saw it doing an automatic repair and he cancelled it. And it was after that I tried to turn my desktop on.

@redxps630 I haven't been able to try this yet but as soon as I do I'll get to you

@RoHe it blinks an amber colored light at the power button. Three times at intervals and just kept on blinking

@DifferentSun   According to the manual, 3 blinks = System board, chipset failure.

So definitely try clearing BIOS by removing the motherboard battery and pressing/holding power button for ~30 sec as was suggested. Then reinstall the battery - probably good time for a fresh CR2032 3-volt coin cell (~$2). Check the manual for details about removing/replacing the battery.

@redxps630 

@RoHe 

Cmos battery is not a fix for corrupted damaged hard drive. I have never seen automatic repair work or solve this issue ever.

There is MUCH LESS To do by replacing the hard drive than tearing it down to get at the CMOS Battery. If new battery is needed they are not expensive.

https://www.amazon.com/dp/B07GN8ZYZR

@DifferentSun  try the drive with reinstall media first.

Either way you will have to remove the stand then the back cover to get to the drive.  Cmos battery is further buried under other metal covers and not easily replaced.  See the links to the service manuals in my previous posts.

3, 4       3 blinks followed by a short pause, 4 blinks, long pause, then repeats Storage Subsystem failure

Possible storage device configuration in progress or storage subsystem failure. narrow down the issue by removing the storage on motherboard to determine which one failed.

3, 5     3 blinks followed by a short pause, 5 blinks, long pause, then repeats Memory configuration or incompatible error

Memory subsystem configuration activity is in progress. No memory modules were detected.narrow down the issue by removing one by one
the memory on motherboard to determine which one failed.

@speedstep This seems to be the problem according to the technician I asked. So he'll come around later this week to get it fixed up. Thanks for your help and concern