My iMac refuse to start in a normal way

[GGERARD]

Hi!
i've a serious problem with my iMac ( end 2017 - 16 Go RAM - CATALINA -Fusion Drive ).
It refuses to start normally. I need to push on the switch during more than 10 seconds . If not, the white running line under the Apple stops in the middle and the iMac is blocked. I've tested all what is possible, PRAM, SMC, Clean install ( more than 5 times !!) Cmd+R , etc... and it is always the same issue. I've called APPLE's hot line........ not efficient at all. The last suggestion was to give my computer at the repair service.
After it starts with my finger on the button... all is more than correct. No bug, no issue, all is perfect.
I understand nothing. It's my 6th Mac, I've never seen that.
May be, If somebody can help me?
GGERARD

 

[macintoshmac]

You really should take it to the store for a quicker resolution than have forum members here conjecturing with regards to what might be happening and wasting time. Anything with respect to the button could be wrong.

 

[GGERARD]

OK macintoshmac, you're right.
I will follow your advice but I was hopping somebody had this problem too and if the case what he did.
Thanks for your answer
GGERARD

 

[Fishrrman]

What happens if you try a "safe boot"
???

Safe boot:
- press power on button
- IMMEDIATELY hold down shift key (keep holding it down about 15 seconds)

 

[GGERARD]

Hi! Fishrrman,
Safe boot is OK but it isn't a solution.
For the moment my iMac is always opened and stays opened all time.
I've called a repair store close to my house and I've to bring my computer to morrow in this store.
It's a store recommended to me by Apple Hot Line.
Thanks for you answer.
GGERARD

 

[ApfelKuchen]

Does the Mac fully shut down? That long press of the power button suggests you have to force the Mac to restart, rather than do a normal startup.

You're currently leaving the iMac on at all times (which is what I normally do with my iMacs). Are you having any troubles waking it from sleep?

Finally, it may pay to test with a new Administrative user account: https://support.apple.com/HT204443. If you are booted to that new account and then shut down, does the startup behave normally, or do you still have the same problem?

 

[Fishrrman]

OP wrote:
"Safe boot is OK but it isn't a solution.
For the moment my iMac is always opened and stays opened all time."

But safe boot DOES show you that the Mac can boot and get to the finder (you DID try to "get to the finder", didn't you?)

If the Mac won't boot to your "regular" account in a "regular" startup (that loads custom extensions, start up items, etc.), but it WILL boot all the way to the finder using "safe boot", then that suggests that there is SOMETHING in your user account someplace that is mucking things up.

Pay attention to what Apfel wrote in reply 6.
Try this:
1. Boot IN SAFE BOOT and get to the finder
2. Go to the users & groups pref pane
3. Click the lock and enter your password
4. NOW...click the "+" sign to create a NEW account
5. MAKE SURE you give it "administrative privileges"
6. Once done, log out of your account and log into the NEW account

Can you get this far?
What happens if you SHUT DOWN (all the way off), the press the power button?
Can you get to the login screen?
If you log into the NEW account, can you get to the finder?

 

[HDFan]

If not, the white running line under the Apple stops in the middle and the iMac is blocked.

There are two white lines. The first, thinner line happens while the kernel is loading. The second happens when launchd starts up the non-kernel processes.

Knowing where the system is hanging in the boot process helps in figuring out whether you have a hardware or software problem. A bad kernel extension or daemon can cause hangs. Etrecheck is a tool that can help with software diagnosis.

 

[GGERARD]

Good Morning ( In France ) and thanks for your answers.
I've tried to create a new account with a new clean install yesterday evening and .... it is always the same.
I've erased " Macintosh data " and tested Macintosh HD alone without any other application than those given by Apple..... and the the result is the same. Blockage the white line in the middle. I've tested to switch the computer with my finger on the button in a safe boot .... and it runs perfectly.
For the moment, I'm trying to re-install Catalina for a new time and i go to the repair-shop this morning.
regards
GGERARD

 

[GGERARD]

Hi!

just to send to you this short message. My iMac comes back from the society " Switch " in Belgium which was recommanded by Apple's Hot Line. They are very efficient and full of Kindness.

It is like a new Mac. All is perfect now I followed the very good advice from macintoshmac.

This Premium Resseler certified by Apple have totally clean my Mac and reinstall the system. I've done that many times but I think I haven't the sames tools!!

Thanks for all of you.

GGERARD