PRAM Reset Apple Logo Not Appearing 10.13.6

[dspdoc]

2017 5K iMac: Can someone put my mind at ease here and tell me if this is the new norm; When attempting a PRAM reset on the 2017 5K iMac running 10.13.6 the Apple logo never appears on the screen indicating to release the CMD-OPT-P-R keys. Instead the screen starts out totally black, then bright, then black. Is this the new norm?

Thanks

 

[LDec]

You have not mentioned if it gets you to the Login screen .
If it does I wouldn't worry and would Login and after perform Disk Utility.
If not ...
Do you have anything other than keyboard/mouse plugged to your iMac?
If yes, please unplug even Ethernet cable and try to do PRAM reset ...
Keyboard and mouse can be plugged, you need it for PRAM rested