iMac has no display screen upon power up

[Rexopell]

Any apple gurus can kindly help to troubleshoot my iMac? Just brought it to sls for servicing 6 months ago over the same problem :/

Upon power on, it has the usual start up chime. I can hear the volume button when I press the keyboard too. However, there is no screen display. Any idea what could be at fault?

 

[B772ER]

Any apple gurus can kindly help to troubleshoot my iMac? Just brought it to sls for servicing 6 months ago over the same problem :/

Upon power on, it has the usual start up chime. I can hear the volume button when I press the keyboard too. However, there is no screen display. Any idea what could be at fault?

Perform SMC and PRAM reset, failing which, try to boot up to Safe Boot. If nothing comes up in Safe Boot, try booting to Recovery. If the recovery screen does not show up, we definitely know it's hardware - either GPU or LCD faulty.