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T420s won't power off

Posted: Sat Aug 29, 2020 6:29 am
by asherxo
I'm new here. I was a lurker for years, finding information on maintaining my thinkpads although I have a lot of problems with them. Until now.....
I've got a T420s for years. It's my main PC. I've upgraded it many times (1080p, SSD, 16GB..) and I'm currently using it for working at home. I'm using the minidock a lot. I dock/undock twice a day and perhaps that's the cause of my problem I've got now. BTW: I already ruled out: broken cmos-battery, broken powerswitch (swapped keyboard already), broken battery. They all work fine. And I already tried all combinations of powering on/off with/without battery/power cord, docked/undocked.. These are the symptoms: - I can't switch off my laptop with the power button. Even when I keep pressing it half minute.
- When I send an ACPI poweroff in software it shutdows down like it should, the power button led switches off and immediately after that it switches on again.
- I have to remove the powercord and the battery to switch it off.
- When I insert the battery again it does not switch on automatically; I can start it with the power button.
As said, it all started after a couple of days working with the Mini dock. I'm afraid I shortcutted something in the connector at the bottom of my laptop. I tried to clean it with compressed air.

Any ideas? Can I disconnect the dock connector somehow? I can live without a docking station. But I get tired of removing the batterypack in order to shutdown my laptop and I can't live without a thinkpad :-)

Re: T420s won't power off

Posted: Sat Aug 29, 2020 2:57 pm
by atagunov
Hiya, what does the power button on the minidock do?

Re: T420s won't power off

Posted: Sat Aug 29, 2020 8:21 pm
by TPFanatic
I encountered a fairly damaged T420s that exhibited this phantom shutting off and turning itself back on again randomly... I wound up replacing the motherboard to "solve" the problem.

Re: T420s won't power off

Posted: Sat Aug 29, 2020 9:56 pm
by axur-delmeria
Did you leave the laptop docked to the Mini Dock for days, powered down, but with charger connected to the AC outlet?