I am having this problem with my Dell Precision 5510 laptop where sometimes the machine would not go to sleep if I close my machine's lid. I am actually running Arch Linux instead of the official Dell Ubuntu distro.
I know that sleeping normally does work when closing the lid since most of the time, my machine would feel cold when I take it out of my backpack. But this is starting to become more of a problem recently where my machine would be burning hot when I take it out of my backpack. I am worried that my laptop will not last for long if this keeps happening...
I am not sure if this is an improper configuration of Arch Linux or a hardware issue. Has anyone else experienced these problems?
This is probably caused by the following ACPI error, which is due to Dell's broken BIOS. It is a known issue it seems:
[200729.138383] ACPI Error: [\_SB_.PCI0.LPCB.H_EC.CHRG] Namespace lookup failure, AE_NOT_FOUND (20160422/psargs-359)
[200729.138393] ACPI Error: Method parse/execution failed [\PNOT] (Node ffff8ad82d0e05c8), AE_NOT_FOUND (20160422/psparse-542)
[200729.138404] ACPI Error: Method parse/execution failed [\_SB.AC._PSR] (Node ffff8ad82d0f3b68), AE_NOT_FOUND (20160422/psparse-542)
[200729.138748] ACPI Exception: AE_NOT_FOUND, Error reading AC Adapter state (20160422/ac-128)
There is another thread en.community.dell.com/.../20006889 with more discussion around the topic of ACPI errors