Macbook 2.4 2008 after update 10.6.8 and firmware, won't fully boot

Question

Weird problem after updating to 10.6.8 from 10.6.0 (fresh install).
I went thru Software Update, it downloaded 10.6.8 and the other updates. It also found that I needed a Firmware Update, which I also choose to install.
The updates went thru okay, including the Firmware. Everything went exactly as it should. The machine booted as per normal.
Afterwards, I checked that it had updated normally to 10.6.8 and everything checked out okay. 
I left the Macbook plugged in and in Sleep. It was like this for probably 24 hours. NO BATTERY INSTALLED (don't know if this could be a problem, but I don't see how). I just came back now to find that I can't get back to the desktop from Sleep, nor can I boot to the desktop.
Specifically, here's what I see:
- first, on trying to Wake from Sleep, the screen remained black. The Superdrive spun up, the white light at the front of the Macbook was pulsing. But no desktop.
- I then held the Power button till it shut down. Then rebooted. And here's what I got:
a) no startup chime
b) I could Superdrive and fans and HD spin up
c) the display turned on, but didn't show the startup screen, no Apple logo, etc. It just went to the Desktop in about 10-15 seconds.
d) on the Desktop I can see:
- the Desktop background
- the Disk Utility window open to Repair Permissions, which was the last thing I'd done on the Macbook (permissions checked out okay)
- and THIS: I've never seen it before, but the Desktop is a bit "fuzzy", I can see the background and the Disk Utility window though, as well as a NUMBER OF SHORT BARS towards the bottom of the screen, and there's a BAR BY BAR PROGRESS from left to right (the first bar is filled in, then the second, etc.), BUT the progress DOESN'T make it to the last bar before the SCREEN GOES BLACK AGAIN  (*sorry for the caps, but I'm trying to highlight the salient parts).
Any ideas?
Is this somehow related to the Firmware update? I remember that the Macbook booted fine after the Firmware update, the long horizontal progress bar was filled in as normal and got to the end; IIRC the Macbook then booted fine. I believe it was at this point that I repaired Permissions. Then left the Macbook, only to return to find it as it is now.
Any help much appreciated.

Answer 1

Update:
Installed 10.6 and did all the updates, am now using it with an external monitor. Working fine as a Mini, but a real bummer re. the black or blue screen.
Without external monitor connected, I get this:
- I can boot, with startup chime, from DVD or external hard disk, after holding Option at startup and choosing bootable volume on screen; I can also boot from the DVD by holding down C key
- When I boot, the startup chime doesn't sound right away, as there's a short delay; in that time (a few seconds), the LED light at the front of the Macbook FLASHES 5 TIMES; there are NO error beep sounds
- The boot screen starts up, I get Apple logo and spinning wheel, and at about the usual point where the screen goes blue for a couple seconds, before the Macbook boots to the desktop, the screen goes black
- The Macbook seems to go to Sleep, with the screen black; the front light pulses
- I can wake the Macbook from Sleep by pressing a key
- Previously, after waking from Sleep, the Macbook went to the desktop -> in other words, the Macbook completed startup with the black screen;
- When the Macbook woke from Sleep, there was a slight delay of a few seconds before the Trackpad and Keyboard became active; I then had a few seconds to use the Trackpad before the screen went black again, and the Macbook went back to Sleep
- Now, though, when I wake it from Sleep, I get a Blue Screen, and the screen stays blue; i.e., doesn't turn black and the Macbook doesn't sleep
All of this refers to booting the Macbook without an external monitor connected.
When booting with an external monitor, everything works normally.
POINTS OF PARTICULAR INTEREST:
1) all of this happened from the time I updated the Firmware, as per Software Update
2) the screen works during the boot process, then goes black
3) boot completes even with black screen
4) the screen works for a 10 seconds when Macbook wakes from Sleep, then goes black again
5) now, the screen goes blue - and stays there - when the Macbook wakes from Sleep
6) Macbook works normally with external monitor; the Macbook's internal display is not recognized when an external monitor is connected; the iSight camera is not recognized
So, what the heck happened?
I can understand the internal display and/or onboard video getting broken, but then it should simply not work at all, right? How is it that it works "partially" or "temporarily", during boot and when waking from Sleep, before going black?
What is with the 5 flashing LEDs at boot or when waking from Sleep? (I can't find any info concerning the Macbook and 5 flashing LEDs, but only concerning the Macbook Air, and it refers to a battery problem).