Hello,

my Dell XPS 15 9570 has problems to start up. Sometimes it does nothing pressing the power button, sometimes it flashes the keyboard backlight to power off after a couple of seconds and sometimes it just boots normally.

Quite often it says, that the service tag is not defined in the bios and I have to enter it.

I already replaced the CMOS battery - but it didn't resolve the issues.

I noticed that I have bios version 1.31.0 but the latest version supported on the dell drivers page is 1.27.0. I guess that the 1.31.0 came with an update within Ubuntu (in fwupd.org it is the latest version for my model: https://fwupd.org/lvfs/devices/com.dell.uefie4d7bdc4.firmware)
I tried to downgrade my bios to v1.27.0 that ended with the message that it is not possible.

Happy about any advice - thank you!