iMac won't start after HDD replacement - no chime, black screen, DVD
(originally posted as a comment on this thread My MacBook won't boot, no start chime, just the DVD spinning sound. but my hardware and symptoms are different and caused by my own hdd replacement attempt hence a separate question)
On a 2007 20" iMac after attempting to replace the hard drive - I can't restart the Mac. The original problem was definitely a bad hard drive - I could start and boot from CD or an external drive). Immediately upon closing the case and turning it on I got a black screen, no chime, both fans start briefly, dvd ticks a couple of times, then it repeats itself indefinitely until I pull the plug.
Tried all the key combinations for clearing NVRAM and holding power button down, etc.
Gave up and put it away for 3 mths (have a new mb pro :))
This is clearly some mistake I made in taking it apart and putting it back together (following iFixit instructions here iMac Intel 20" EMC 2133 and 2210 Hard Drive Replacement, since it worked fine but for the hard drive before.
Trying to fix it again.
First I removed the new HDD to see if that was it.
I have a Time Machine backup attached by FW, and even with no HDD I should be able to boot past this point, right? I mean I should at least get past a black screen? So from here on, I'm working withOUT the internal HDD attached at all.
Anyway I removed the RAM on advice in the thread above above - and ...+something+ happened… With no RAM in I get the no-RAM single beep and it seems to go a lot further: fans stay on, lots more DVD noise seems to be trying harder almost like it's actually going to boot, but in the end it gets no further and the screen never changes from black.
Adding the RAM back one chip at a time puts me back to the original problem... Even with just one RAM module in one slot (either one, tried both).
Pulled out the RAM and put it back several times no luck. Also no luck with any of the keyboard options while the RAM is out (I tried holding down T or R or C or Eject with a regular apple USB keyboard while booting - no diff)
Also, what does the fact that it seems to get further with no RAM mean? Does it just mean that the real problem occurs after the RAM check? Or is the problem related to the RAM?
Note that the RAM was fine before I replaced the HDD as was everything else.
I looked for loose connections - and cant find any. Perhaps I plugged the connections between the screen and the MOBO back wrong? What else?
[UPDATE after Answer below]
Thanks for the tip on the LEDS. I have the left three lit and steady, which apparently means all is well but for the communication with the LCD panel. Which kind of makes sense since it is dark.
I tried an external monitor: it also stays dark. Not sure however, if this is not simply because it can't boot to the point where it could drive an external monitor.
I tried plugging back the old - bad - hdd to see if it made a difference (that disk was faulty of course, but I got further than this _before_ I removed it, so I wanted to try to get back at least that state). Makes no difference - so it's clearly something I did wrong in dismantling/assembling.
Note that my "good" disk has never been formatted, so it would not be bootable. And I can't find my original CDROM (I suspect it's actually in the drive but I can't tell - and its been a few months since I gave up on it :))
So where am I now:
- No disk/bad-disk/good-disk-unformatted makes no difference
- removing RAM causes it to try harder (it seems) but fails with missing RAM (all combinations of RAM in/out tried)
- External monitor makes no diff - not sure if that's significant
- Looks like I broke the connection with the LCD during assembly
Any ideas what to look for here? One thing I'm not sure about is whether I have the Inverter Cables connected properly. Could it be that?
Could it be one of the heat-sensors: will it fail like this if they are not connected?
Any other ideas?
Is this a good question?