Function key reversed

[DavidAccolade]

See what you think of this: my FN key is reversed. If I don't touch it it acts as if it's being held down (disrupting the function of various keys with secondary FN functions, like my spacebar. I must hold down FN every time I want to hit space). If I hold it down it acts as if it’s not pressed. This happens even in the BIOS. I hit ESC to get out of a particular BIOS menu and nothing happens. I hold down FN+ESC and it accepts the input as if only ESC has been pressed.

My device:
Satellite L775-S7355
Windows 10 Home
BIOS: American Megatrends Inc. 2.3

Background:
I initially had a weak battery that caused my computer to power off suddenly and caused boot problems. I reinstalled the OS for the boot problems, which is when I noticed the FN issue. (I've since reinstalled the OS again.) (Boot issue is resolved. I replaced the battery.) I know this sounds similar to the common FN lock issue, but I think this may be something more complicated.

Key combinations I have tried that didn’t do anything:
-Hold FN key 10+ seconds
-FN+Esc
-FN+Num lock
-FN+Every other key on my keyboard, one key at a time

 

[DavidAccolade]

Other things I’ve tried:
BIOS:
Per the thread Special keys and F keys seem to have reversed? I updated my BIOS to the latest version and looked for a Function option. There is no Action Keys Mode or Function option to enable/disable, unfortunately. I have photos of each BIOS menu if that becomes relevant.

OS:
-Reinstalled Windows 10 through System Settings > Reset this PC (retained no files)

Software:
-Toshiba’s Function Key: This only has options for “Power plan” and “Touch pad”, no options available for power keys or FN keys.
-Toshiba’s HWSetup: Apparently this application isn’t designed for my model of Toshiba. It doesn’t launch.
-Toshiba’s Desktop Assist: Perhaps I’m misunderstanding the purpose of this application--it seems to only act as a convenient place for shortcuts to other Toshiba applications.

Hardware:
Popped the key off and cleaned under it. No effect.