Run the computer diagnostic tool to check the hardware on the computer by following steps below:
1. Power off system.
2. Power on system. quickly start tapping F12 key continuously until you see Preparing One Time Boot Menu in the top right corner of the screen.
In Dell eSPA Preboot menu, select Diagnostic. After quick tests, select Hard drive and then Thorough Test Mode. Report back any error code
ePSA Pre-boot System Assessment (Official Dell Tech Support):
https://youtu.be/qeHNSxW7VSM?list=PLdLDGmnHB07NVpbsbTGei
Very slowly work my laptop
To better assist you, the members and I would need the exact model number of your laptop/desktop???
Also try this.
Hold down the "D" key, push the power button, release the power button, wait 2-3 seconds and release the "D" key
The laptop should go through an LCD test of solid White, Red, Green, Blue and Black 2 or 3 times.
After completion it should try to automatically boot 2 or 3 times.
Post your results.