Toshiba satellite L775d-s7210 no longer POSTs, blank screen on boot


Aug 7, 2015
Toshiba Satellite no longer POSTS, black screen

I have a Toshiba Satellite L775D-S7210 laptop that refuses to boot properly. I've owned this laptop for about 4 years and this problem just happened a few days ago. It can turn on, but it leads to a blank screen (as if the lcd is disconnected from power) and only the small Power indicator light is lit while the others are off.

It does not show any BIOS or POST screen. While it's on, I can hear a electrical whirring sound coming from the underside of the logic board, and the Optical disc and hard disk exhibit accessing activitity. Then, after a few seconds, the CPU fan starts running.

This laptop stays powered on forever and the only way to turn it off is to hold the power button or remove the charger or battery.

The events that occurred before this blank screen problem was a simple file transfer between the internal hard disk in IDE mode and a cruzer glide 16gb flash drive. Nothing out of the ordinary, just your standard drag-and-drop file transfer.

When i completed this file transfer, i rebooted the PC into the BIOS settings. I was going to install Windows 7 fresh, so I went to the setting that had the options for AHCI or IDE, and changed it to AHCI. I saved the changes and rebooted. On the next boot, I got a blue screen error while it was loading the old Windows 7 partition that was left there. It crashed and rebooted.

On this next reboot, the laptop could no longer boot and showed a blank screen with just the power light indicator on. And, nothing else would work after that (usb, keyboard, etc). It just stayed blank. A few reboots after, only the Power and WiFi LEDs are on, but still no display or access to BIOS.

How could have this problem have happened? It was very, very random and out of nowhere.

Here's what I've tried:

- Remove all connections to peripherals off from the logic board, leaving in CPU only, power button connection and then boot.
- put back one ram stick and cpu and tried booting

- reseat the CPU and put new thermal grease

- connect back peripheral connections one by one and boot each time one was connected.

- Removed hard disk and boot
- swap hard disk and boot
- remove both RAM sticks and boot.
- remove one ram stick and boot each one.
- removed optical drive and boot.
- connected laptop to external display via VGA. No picture still.

None of the above worked.

I'm starting to think its a problem with the logic board, or the BIOS firmware. I am not sure. I can't even reflash the bios from toshiba's support site because the laptop does not even POST. I don't know if somehow changing (not reflashing) Interface settings from IDE to AHCI could corrupt a BIOS.

Also, this is the motherboard model: H000034200. Where is the BIOS chip located on this?

Also, what other troubleshooting steps should I try next?

You've pretty much done all the possible troubleshooting steps and left you with just one which is to reset BIOS to default by reseating the CMOS battery. It should look like a standard round flat battery that's in the mother board.


Sep 21, 2015
I'm almost positive I know exactly what's wrong with- and how to fix- your laptop (if u havent already).
Simply replace your CMOS battery. Not the laptop battery, but the little chrome colored internal button cell.
Alotta times this requires some tear-down & reassembly. Luckily in your case, it's easily accessible under the RAM panel.
In my S775D-S7340 it's a CR2032 with no special packaging/wrapping/plastic. Should be same 4 u.

U can get em for about $4 in ur local drug store. Or u can get 10 or 20 for the same price, if you wait for them to be delivered from eBay.
Very rare issue that usually gets overlooked, only happens after years of use, and in my case, only after multiple other fixes.
Noticed your post was only about 6 weeks old, so I signed up just for you.
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