Bios Mods -The Best BIOS Update and Modification Source

Hi,

Question to BIOS gurus. Completely baffled as to what to try next, any advice highly appreciated!

In a nutshell:
After BIOS update:
a) BIOS doesn't save any changes, apart from time and date
b) BIOS doesn't see the internal hard drive, but sees USB drives.

What I had before:

• I had TPM initialized and active
  
• Secure Boot to Windows 10 with bitlocker
  
• Supervisor password on BIOS
  

Specs:

• AMI BIOS (Aptio 5, apparently) 
  
• i7-5500u, NEC-built/Lenovo-branded laptop (Lenovo Lavie Z)
  

https://goo.gl/photos/XuaZWnQU4S6x97yK7

Issue started after:

• I did a bios update, but (not sure if anything of this has contributed to problems)
  • didn't turn off bitlocker and secure boot
    
  • accidentally only reflashed the main block
    

Symptoms of the issue:

• BIOS is reset (expected)
  
• TPM Support is showing as Enabled, TPM state is Disabled&Deactivated. https://goo.gl/photos/61ABiKQTnocyM5Uj9
  
• Boot: Legacy mode (was UEFI), Hard disk is showing as question marks https://goo.gl/photos/GtkwJSiDxCbycBoj6
  
• No changes are saved, apart from date and time.
  

What I tried to fix:

• reflashing under win (recovery drive) and dos; all resulted in "43: Error -- problem erasing flash" regardless of the bios ROM i'm using
  
• attempted to do the "emergency USB recovery" by pressing Win+B, Control+Home, Home, Fn+R, Fn+B (both on internal and on external keyboard) when powering up and putting the ROM as original filename (763A0400.ROM) or AMIBOOT.ROM. Never worked.
  
• Disconnecting the battery and CMOS battery did reset system time, but hasn't fixed anything.