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ThinkPad NotebooksThinkPad: T400 / T500 and newer T series Laptops
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T420 endless rebooting before post? (4177-CTO)

2013-08-21, 20:38 PM



So I recently started having an odd issue with my T420. Everything was working fine, and I then decided to go into the BIOS and enable the power-on and HDD access passwords. This worked fine, but after doing so, the laptop started restarting immediately after accepting my power-on/HDD passwords.


I decided to go into the BIOS, restore all defaults, and remove the passwords. It worked great and the passwords were removed, but not the computer is restarting before even POSTing. The last message I am able to see while booting in diagnostics mode is "ThinkVantage Active Protection Diagnostics start.../", the "/" spins a couple of times, and the system goes into an endless reboot loop.


I have tried removing the HDD altogether and booting from CD, and booting from CD with the HDD in the laptop. Either way it is not even getting to the point where it searches for a boot device, as it doesn't seem like the system is POSTing. I am able to go into the BIOS just fine, but restoring defaults does nothing.


Any help/input? I am frustrated as my laptop was working perfectly fine up until this incident, and now i effectively have a brick. I am out of warranty, so I am not even trying to contact Lenovo.


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Re: T420 endless rebooting before post? (4177-CTO)

2019-10-16, 20:14 PM

Hello...did u get this problem solved? Bcoz i have the same problem now...please do tell me...

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