12-10-2014 09:16 AM
Earlier today I noticed that my w520 had not gone into sleep mode properly when I shut down the lid yesterday night. The fan was turned on, the CPU side warm to touch and the power button with green led on. The laptop didn't respond to any key or mouse input, so I just pressed and held the power button till the machine shutdown.
Once I turned on the laptop again, pressing the power button, the laptop went into a reboot loop! Unlike some reboot loops reported in this forum, mine does not even display the Thinkpad BIOS screen. The Power LED indicator comes on for a second, with the CAPS lock, Bluetooth and WLAN LED indicators lighting up at the same time and then the machine shuts down and reboots again and the whole thing starts over again. The only way I can stop the reboot loop is to press and hold the power button for about 10 seconds once the power is on for the brief period. Turning on the machine afterwards again results in the same reboot loop!
So far I have tried taking out the battery and tried starting it using power from the docking station and same thinng keeps on happening. I don't have an external monitor at hand right now, so I can't even tell if it's some weird display driver issue. I haven't taken out the primary hard drive (256GB SSD) and trying to boot yet. Will report back when I do.
In the mean time, any helpful suggestion on how to troubleshoot things further?
12-10-2014 09:57 AM
05-04-2016 02:00 PM
This reply is a bit late: try to remove the BIOS battery (small coin-size battery). It's located under the keyboard - see the hardware maintenance manual if in doubt. Remove it for some minutes without power supply or main battery attached.
07-21-2019 08:58 PM
If you have 2 DIMMs try them one at a time. If you only have 1, can you get another stick to try
07-24-2019 06:22 PM
w520 i was wondering if you ever found a solution to infinite restart loop....i should have never changed bios numerical control...that cause this loop now i cant access bios ,,tried everything,,,did you find a solution?
07-24-2019 06:27 PM - edited 07-24-2019 06:30 PM
i was wondering if you found a solution to reboot infinite loop...for w520...when i was in bios i changed numerical control and this cause dthe loop issue,,,i have taken out ram and hardrive,,..tried boot cd but that did not work i dont know what to do,,it is stuck in black screen restart mode,,,,did you find a solution? I used to think ibm thinkpad was the best but after lenova took over their software is crap and so is the hardware,,but i have a few w520,,i like the keyboard layout so i keep them as work horses,,,could you please help me thanks Doug here is my email firstname.lastname@example.org
07-25-2019 04:58 AM
I haven't found a solution yet. I even took out the bios battery. Interesting that you mention changing the bios before the trouble started, maybe in your case a bios reset will fix things.