Solved Win 8.1 stuck on shutting down sreen after BIOS upgrade

Hi,I have a GIGABYTE S1082 which I upgraded from Win 8 to 8.1 via the store.

Problem: After the upgrade it began to run into problems: Shutting down sometimes worked while at other times the power button was the only way out. Disk usage was constantly at 100%. I was able to fix the disk usage problem by reconfiguring the page file.

Solution attempts: To get rid of the shutdown problems I upgraded the GIGABYTE Smart Update application (to 2.4.6 I believe) and began to upgrade all my drivers from top to bottom, rebooting after every change. The shutdown problem, however, did not go away before I arrived at the BIOS upgrade. Upgrading the BIOS itself worked without error.
When the Shutting down screen appeared, it would not shut down. I left it plugged in over night and after about 8 hours it was still shutting down. Growing desperate, I attempted to shut it down with the power button which to my dismay did not achieve anything except freezing the spinning circle next to shutting down.
The mouse and multitouch panel are still responsive. Fan speed is changing and I can hear the hard drive working. My WiFi access point lists my tablet as currently connected.

Suspicious things: Errors in the application log earlier said "Cannot restart [a lot of standard windows components like explorer.exe]: Application SID does not match Conductor SID". Also GIGABYTE Smart Update says that my bluetooth driver (which Windows wants me to reinstall after upgrading to 8.1) is already a version newer than the latest one available for download and therefore refuses to install the latest version. I have no idea what to do now. Any help would be appreciated. I guess I can only let it run out of power and see if it will work when I plug it back in.

Note: I did create a custom RefreshImage.wim when the PC was more or less working.

Solution: Letting the battery run out and then restarting normally solved the problem with the BIOS upgrade which in turn solved the problems I had with Windows 8.1. If you have an S1082 and problems shutting down, sleeping, hibernating and restarting I recommend you upgrade your BIOS to version F30B / F204 or newer. Even though the BIOS upgrade installer warns to not power off your device it may just be the only thing you can do - and it may actually solve the problem. As you can see below my BIOS did actually run into a problem afterwards which is why I do not recommend cutting the power. I might have been very lucky that the BIOS only had a minor problem.

Note: After shutting down for the first time after letting the battery run out the battery charge display feature of the S1082 (which can be activated by pressing the volume down button while the device is off) did not work. However, it worked after the second shutdown.