After long storage: Fans running, but NO startup chime or display.
My 2017 27" iMac had the logic board replaced just over 12 months ago. It was working fine after that. I moved overseas, and it went into shipping for 3 months. On getting it back about a fortnight ago, it would not start. Where I am currently stationed, there are no Apple Stores or approved Repairers.
SYMPTOMS
- Power switch works, and fans come on.
- No startup chime.
- Nothing on display (remains black).
- If I power it down by holding power button, it turns off, but then starts back up again after a few seconds. I have to remove power cable immediately it turns off to keep it off.
DIAGNOSTICS
- I have removed the RAM. If I try to start it up without RAM, it produces the 'no RAM' beep, but symptoms remain the same.
- I have removed the display screen. LED 1 lights up when power cable is plugged in. LED 2 lights up when I press the power button. Fans run high (as expected with no display). LEDs 3 & 4 do not light up.
- There does not seem to be any obvious damage or poorly connected cables on the inside, although I have not yet taken off anything other than the display screen.
WAY AHEAD
- I cannot replace the iMac, nor can I get one shipped to me, due to where I am currently deployed.
- Is there a PRAM battery in these models that could possibly be drained down after 3 months unplugged? Could that cause the symptoms?
- Is my only option to get hold of a new logic board and replace? Sadly, that is probably more expensive than the iMac is worth.
Thanks to anyone who has any helpful advice on what to do next.
J
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