Yoga C740-15IML Laptop power button stays on for 8 seconds and goes off for 8 seconds.
This problem started as an intermittent shutdown problem. Lenovo hardware diagnostics did not identify a problem. Windows 11 has been reinstalled and the drivers updated from both the Lenovo site and the Intel website. Seemed to be good for over 24 hours and then it shut down again.
In the past I was able to power it up after the unexpected shutdowns but now it just stays off with the power button lighting for 8 seconds, off for 8 seconds.
Removing the power, battery and holding down the power button for 30 seconds turns it off but it goes back to the power button 8 second loop again when it is powered on.