Black screen and capslock blinking one time

[Italbd]

Hello dear sir/mam

I have compaq presario cq42. I got black screen and capslock blinking one time problem. Before pc was ok.i just tried to update my keyboard driver and restart it. That time it was off but it didn’t on.afterthat i hold off key and turn it off. From that time It's no display. I clean the fan,board, 

I tried remove ram,  Battery, and hold power button press 1min. After i try to on but same problem. I check the possessor It's ok because possessor is heating. I cheak all mosfet everywhere has require voltage. I tried with multiple ram. But there are no result .what i can do now.i tried also update the bios by holding power button with windows key and B key.but same problem. 

If there are any solution please tell me.

Thanks 

[Echo_Lake]

@Italbd

Thank you for posting on the HP Support Community.

Don't worry as I'll be glad to help,  

I appreciate your efforts to try and isolate the issue. This sounds like hardware related issue with the computer and in order to fix this issue,  your computer needs to be serviced.  As we have limited support boundaries in the support community as of now. 

I would request you to reach out to our Support and our Support Engineers should be able to check the available service options in order to diagnose the computer physically.  HP Support can be reached by clicking on the following link:  www.hp.com/contacthp/​​​​​​​

You can also refer the document: Computer Does Not Start and Emits an LED or Beep Code

Please feel free to contact us here anytime you need any further assistance. Please click “Accept as Solution” if you feel my post solved your issue, it will help others find the solution.