See my flow chart on topic here:
There are only 2 causes.
  • PC hardware bad. (see page below)  (if the screen is dead this is hardware failure and if BIOS hot key screens are dead, the same)
  • PC Operating system bad (reload it)
In all cases the monitor or LCD screen can be dead. (see tests here)This too is hardware failure. (but  needs to function correctly first)   <<< for sure get the screen working first or we can not do more testing.
Do the hard cold boot reset now.(power)

A dead PC has over 20+ possible causes;  (not at once)
A dead PC might even have 2 things wrong, and happens all the time on old PC's.
The 2 most common failures bar none !, are all bad batteries in the PC are dead, or bad or far worse shorted.
One top question seen on vast forums is "can I fix my dead PC", we do not know your skills or tools nor if you can remove 35screws inside any laptop and not get lost. (or make it worse)
Windows 10 has over 100 BSOD screens and causes. (below is #1 and classic and is a  hardware error) "Microsoft documents them all if you look there." BSOD = blue screen of death.
Before condemning parts bad we first remove all USB media devices , be that Thumb drives, external drives or external DVD drives and all internal CD/DVD disks in any DVD tray , now gone.

There are only 2 macro causes of failure, one is hardware and the other is Windows corruption (or what ever OS you run) and bad hardware can cause, guess what? Windows corruption!
In the micro sense over 20+ things are the possible cause. (dismantle any PC into a box of 20 + parts you  see that if any of those, are shorted kills most PCs dead as a door nail)
Windows 10, did  you cold boot the PC 3 times to see W10 goes into self repair mode,? after fixing bad batteries below? (if not done right you go into an endless boot loop)
  1. Bad Batteries top  the this list, for sure the RTC coin cell dead, or worse any laptop huge battery inside, is dead  or worse shorted. The latter we just remove it and run on AC power to test the PC.
  2. The HDD is bad, this can happen on only 5 years of usage.  We test it 3 ways, but on dead PC there are 2 ways the makers diagnostic or boot this Linux demo disk and see if DiskTest fails.
  3. or remove the HDD boot drive and move it to a 2nd good PC and run this free safe app.?
  4. On old PCs the HDD or SSD boot drive my be totally full and this must be cured first . (I use Linux demo boot media to clean off useless files) "boot Linux install disk and click TRY ME"
  5. PCs can overheat in seconds (15s?)for sure faster on more expensive PCs. We clean those PCs of all lint and dust first..
  6. Next is the BIOS dead or not, if not dead and the BIOS hot keys and screens for them all work, go into BIOS and set the boot order drive as first. In boot order page. Now the good HDD above can actually boot;
  7. Does holding the power button for 10 seconds and release the button allow PC to boot and run?
  8. Try windows 10 Safe mode yet?   (boot PC 3 times and  (there are 5+ ways go gain SAFE mode on working PC but only 1 or 2 for dead PC.)  see my safe mode method  just  below.
  9. If all cures fail try doing  a strip down test. (any of 20+ modules in any PC can cause PC to be Dead)

SAFE mode H3LL, on a dead PC, a working PC is easy but is off topic on any Dead PC.
The PCs RTC coin cell must NOT be dead. (and boot order must have HDD/SSD boot drive first )  CD/DVD try empty and no USB thumb drives inserted.
If the HDD is bad, all steps forward below step 2 above are a huge waste  of time, and ZERO GAIN.  Learn the skill of testing any HDD ,using a Linux boot demo media or moving suspect HDD to external drive and test it on a good PC.
NO OS on earth runs on a bad HDD. This must be clear in your head first. (nor can it boot with a bad RTC coin cell battery)

Some times booting 3 times on DEAD W10  , gets you to the recovery screen. (and advance mode and SAFE MODE) Do the hard cold boot reset now.

A Dead PC makes W10 hard to reach safe mode, for sure if boot 3 times fails below.

The below means the HDD/SSD boot drives is dead, corrupted or is simply turned off in BIOS.

BSOD #1,  (the boot hard disk drive is dead (so it seems)...  try booting cold 3 times. Cold means from 100% turned off doing this , long hard cold reset.

after 3 times you will see choice auto repair.

If the Automatic Repair could not  repair your Windows 10 PC problems, you can click Advanced options to enter into Windows Recovery Environment screen to try other options to repair PC.

Enter into Startup Settings

In the WinRE window, you can then enter into the Startup Settings window by clicking Troubleshoot -> Advanced options -> Startup Settings -, SAFE mode then > Restart.

See my 2 cures here, for W10 self repair. (Safemode and fast boot turned off and hibernate turned off)

Off my site cures:

See method 5 here, for black screen PC.

A Proactive stance?
On the same page see method 6, for future much easier SAFE mode access using BCD way.
I use EZBCDedit. exe to set up fast mode and 3 second time out.  (link to actual maker)

Now I can go to SAFE mode in 1second flat at boot time. every time. (my timer set to 3seconds there)


When I state "HDD" I mean those and SSD or m.2 boot drives. (just to save typing that every time)  I mean BOOT drive no matter what it is.

version 1.  10-1-2020