Lots of answers here: HP PCs - Computer starts but the screen remains blank (Windows 11, 10) | HP® Customer Support

 

Sounds like pad psu doesn't have enough power to boot to me. See if you can another one to try and that's where taking it to a repair place they can at least test the components to find the issue which definitely sounds like hardware.

 

Hi, can you see the Hp logo once you turn the pc on? If you didn’t see the logo it’s mean that there’s no signal from pc. However, try to use the other port (DP) other than the HDMI port.
finally, if the monitor doesn’t work. Turn off your pc, unplug all cables, take the RAMs out. Now, press and hold the power button for 20 seconds. Re install the RAMs back. Connect the power cable and turn the PC on. It should work fine now.

 

UPDATE: Is it the ram? I tried to put the RAM from the PC into my laptop so it would run faster but when I did I got no display from the laptop and it didn't boot just like the mini pc did.

 

If the ram hasn't got the specs required then a black screen is a normal response.I have2 laptops that have compatable sockets. One uses/takes DDR3 ram the other DDR3L ram. If I try swapping the ram between the 2 then both give me a black screen and no boot. In spite of the manufacturer stating that one of them should work with both DDR3 & DDR3L.
Normally laptop memory and PC memory are of different size so you can't swap them out. They don't fit the sockets.
Not sure about your particular situation but on my DDR2 PC, I have to insert 800MHz cards, if I try a slower card, it also goes black screen, the MB specs state 800MHz or one speed higher, even 1333Mhz is not approved. I found out the hard way!!

If the specs of the ram that you are swapping are not identical there is a good possibilty that the device will not boot!

 

Further to above, if your ram is missing from the Prodesk do you get warning beeps from the Motherboard ?
With the correct RAM installed and your display unplugged from the motherboard, do you get warning beeps from the motherboard.
Have you tried a different display?
Since the unit was in transit before you turned it on, ha e you checked the graphics card to see if maybe the connector got damaged or may not even be seated correctly in its slot. Also check the connector on the cable to see if that has a problem.
You say you have a laptop. Does it have a compatable socket for the displays cable. Try it to see if the display works there.
Finally, was the Prodesk being used elsewhere by someone else with a different display. Perhaps the display settings were adjusted manually and are not compatable with the display you are trying to use now.

 

to expand, the pc was working fine a day before it stopped working. I ordered more ram (made sure it was ddr4, pc4, etc) but after what you guys have told me about the MHz, I don't know if I got the correct ram for the system, and from what I understand even if every thing else is working, it doesn't matter if the MHz aren't the same. Worst case scenario it doesn't work and or the ram isn't the problem I'll probably just return it and use the money to buy the correct components. I'm gonna try the ram now, says it's compatible with multiple types on the box.

 

so I just plugged the pc in and all I heard was a single beep, right now it just turned on and it said "this system time is invalid and it may result in battery loss." it just turned on now and appears to be working.

 

hey, currently typing from the pc, I think everything is fine, upgraded from 8 gbs to 16 gbs, but this pc has a history of breaking so I will report back here if anything goes wrong. Thank all of you guys for the help you've given me over these few months .

 

Just to clarify, since it's not clear what you actually did and to what.
You ordered new Ram, installed it in the Prodesk. Powered on, you heard a single beep as it started up, booted and your display is working again normally.

Well done !! Glad to hear the good news!!

You actually reminded me now of some weird faults that came to me from a client when I was working. On many occasions, one of our "techs" would be sent out to fix one of our clients many computers. He would take out a replacement PC and bring back the faulty one having failed to see or find anything wrong with it.
I too would check everything for obvious signs that something had failed without joy.
Very similar situation to your problem except that it hadn't been transported anywhere.
To faultfind, my first port of call was to figure out whether the Mothernoard was trying to do anything or was just sitting there dead. The Motherboard BIOS, if you ever wat h the display as it boots, tests memory then goes on to test other hardware. If there is a fault with memory then it gives off a series of beeps as warning. I removed the RAM after removing power, then powered on again. If the Motherboard gives off a series of beeps then you have a good idea that the mptherboard is trying to do its job at power on.
On these occasions, after hearing the warning, I would power off, reinstall the ram, and then power back on again only to find that the PC would now power on normally. This happened on many occasions and I have no proof as to why. I assumed that somewhere in memory an important data bit, maybe in the cpu, had got stuck in the wrong binary position blocking the ability to power on normally.
Removal of ram plus power on seemed to flush the problem clean. I don't ever remember the same PC returning for the same problem, and I kept records for the history of each machine.