Assuming you mean Checking NVRAM.
Have you installed more memory recently, is so take it out and try booting.
If not check all chips seated properly, if they are remove 1 at a time and try rebooting.
What is ransomware and how do I protect my PC from WannaCry?
What I learned from my mentor, Oscar-winning VFX supervisor Phil Tippett
Siri vs Google Assistant
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