Solved! Dell 7577 black screen w backlight off

Oct 8, 2018
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7577 black screen w backlight off
Hi. My 7577 won't turn on. The laptop starts with a black screen, screen backlight off. There are a few things that happen when I press the power button:
1) Only keyboard backlight is on without fans starting (silent). This goes on for 1 minute 20 seconds or so (if I don't do anything) and laptop shuts down the moment fans start.

2) Same as the first case but I press the power button again while keyboard backlight is on, fans start like it does on a normal startup and laptop shuts down after 3 seconds.

3) Keyboard backlight is on and fans start normally but laptop shuts down after exactly 30 seconds.

4) I hold "D" button on keyboard and press power button. The screen shows a few colors and laptop shuts down after exactly 30 seconds.

This happened when after I pressed F8/Shift+F8 several times during boot to enter safe mode. (I was going to fix a problem where I installed a program called WindowBlinds that changed windows explorer's appearance but instead was killing explorer. I could use task manager and some stuff but other than that it was a black screen and couldn't start explorer from task manager>new task.) I have removed all usb devices and power source as well but still can't boot.

Please know that sending the laptop to dell support is not an option.


Any help and diagnostic tool knowledge like pressing "D" on powerup is appreciated. Thanks in advance.
 
Solution
Sounds like a motherboard issue, try removing the main battery, the CMOS battery if there is one, hold in the power button for about 30 seconds, plug in wall power only and see if system turn on. Hitting F8 should not have caused the issues you are seeing. Maybe bad RAM or a drive connection, but most cases like yours ends up being a motherboard issue.
 
Oct 8, 2018
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I did. When I plugged in without battery, it fans started at full speed. Still same issues after plugging the battery in, but now with fans at full speed. Don't tell me I screwed something up ? :/
And by the way this had happened after a change in BIOS. I had set fast startup to "auto". I still think it is bios related and if I reset it it'll get fixed. Any other recommendations ?
 


Removing the CMOS and main batteries would have set the BIOS to default settings.
 
Solution