Help with basic H/W troubleshooting steps

Hi,
I am posting here as I am abt to try for a entry lvl basic helpdesk support/onsite job.I am comfortable with OS and networking troubleshooting but however,I do not have much exp in the H/W side and therefore I would like to gain more exp in the H/W side and would like to prep myself in the event of any H/W fault reported.Being a laptop user for most of my life,the problems I encountered so far was unable to boot up and a hard-reset by pressing power button for awhile did the trick.

I have 2 scenario which I had no experience before and researched to come up with the steps with some qns and would appreciate advice
:)

Scenario 1:PC cannot boot up.no beeps
From what i read,when there is no beeps,it means either PSU,CPU or MB is faulty..So my steps are listed below(Let's imagine that every step done is still not successful and therefore there is a,b,c,d etc...)
a.Remove AC and USB devices and hold power button for ~30sec.(only for HP PCs?)
b.Check Power cable to see if inserted properly.Change to another power cable and also check if AC powerpoint is working
c.Check to see parts are inserted firmly.
[In the event if there is no spare PSU,how to check if PSU is faulty?]
d.Take out all RAM and to see if any beep.If beep means motherboard is ok,no beep motherboard potentially faulty?

I read that to check CPU,take out CPU cooler and power on,if there is some heat coming out,it means that CPU is working,is there any alternative option?


Scenario 2:PC cannot boot up.have beeps:
-refer to BEEP code to see which HW may be faulty

Scenario 3:If Laptop cannot power on after doing the hard reset method with no beep,How to I proceed from there?