dell single beep - sometimes works fine

[Arravind]

Dell Inspiron 15 r sounds single beep when started and nothing comes in display.
Fan starts and stops. But single beep continues.
After continuously trying many times it starts and boots to windows.
Hardware health check from within windows shows no errors.
As far as I have searched in dell laptops single beep is for motherboard issues.
But how does it start once in a while?
Laptop is not within warranty.
Is there some pointers and what to check?
Have already removed ram and battery and retried.
But no use.
Thanks in advance for your suggestions.

 

[BadAsAl]

From Dell:
# of Beeps: 1
Description BIOS ROM checksum in progress or failure
Possible Cause(s): System board failure, covers BIOS corruption or ROM errors.

So could also be issues with BIOS. Maybe try updating or reflashing BIOS? I would do it from bootable USB just to be safe.