Another new BIOS release for this buggy laptop.
The good news: after several months, the 'brightness flickering' issue introduced in an earlier BIOS update now finally seems fixed.
The bad news: a new bug seemingly snuck into this new release. Since the BIOS update, when closing the lid, my laptop crashes. Reopening the laptop restarts the laptop entirely.
After further investigation I noticed it not only happens when closing the lid. Merely selecting 'sleep' from the shut down menu will trigger the same behavior.
Possibly related to one of the fixes in this BIOS release since it states "Fix Lid close can't switch display issue." With Dell's utter lack of regression testing (or mere testing?) I wouldn't be surprised this fix created new previously unreported problems.
Luckily (for now) I seem to have found a solution.
After having updated to BIOS 1.2.18, what seems to be needed is a clean full shut down from the shut down menu. After having done this my laptop (for now) is capable of going to sleep again.
Possibly, the issue was related to some other software running on my laptop, however, in that case I would imagine a 'crash' to be the near equivalent of a full shut down (thus resolving the issue after the first crash). Therefore, I find it more likely this issue had something to do with some of the changes in the BIOS.
seems to be better for me after a clean full shutdown.. let's see if it lasts. Will prevent me from having to mail it to Dell