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oifovo
Paper Tape
Posts: 2
Registered: ‎11-27-2017
Location: GB
Views: 6,254
Message 1 of 3

Hard Bios reset without monitor (T420)

Hi guys and gals, 

 

My first post on here so please bear with me! I have a T420 with Nvidia discreet graphic card and today I was messing around with BIOS because the laptop stopped switching to Nvidia and would only run the integrated GPU. To cut the long story short I went to Bios and changed the settings to force the laptop to use the NVIDIA card only (OS detection for switchable graphics disabled and Graphics Device set to NVIDIA). I saved the settings using f10, the screen went black and I haven't been able to do anything since then. When I restarted the laptop I could hear it booting into windows but absolutely nothing appears on the screen. I now need to somehow reset BIOS to factory settings without being able to use the screen. I tried disconnecting CMOS battery but this didn't help, in fact I think it made it worse because now the laptop just beeps when I turn it on. Any idea how to  reset it back to factory settings without anything being displayed on the screen? I tried connecting another monitor to VGA port but that didn't help.

Community SeniorMod
Community SeniorMod
Posts: 9,677
Registered: ‎01-01-2010
Location: US
Views: 6,250
Message 2 of 3

Re: Hard Bios reset without monitor (T420)

Disconnecting the CMOS battery will revert to BIOS defaults.  (assuming it isn't plugged in and the main battery is also out.)  I always let it sit for 5 seconds and press the power button a couple of times do drain capacitors.  If that didn't work, I would guess that a motherboard problem is what caused your nVIDIA graphics not to work initially.   The beeps could be date and time.  Fn + F7 will switch to an external, if connected.


Rich


I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
oifovo
Paper Tape
Posts: 2
Registered: ‎11-27-2017
Location: GB
Views: 6,238
Message 3 of 3

Re: Hard Bios reset without monitor (T420)

Thanks richk! I have managed to get to BIOS by connecting the laptop to my projector and pressing fn+f7. I could hardly make out what was being displayed as the image was all "broken" (not sure how best describe it, it simply wasn't displayed as it would normally be, all the menus would only appear when selected and then disappear again) but I managed to change the boot up display settings to Analog and that helped to get BIOS displayed correctly on my laptop screen. From there on it was just a matter of reverting everything back. Now I need to figure out what's wrong with my NVIDIA but at least the laptop is working again. Thanks for your help!

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