Dell M4600 problem with bios update

My Dell has A08 bios when I try to update to the newest version (A16) there is a information when computer restarts "bios updating failed".
I tried to run update from USB drive (Free DOS) but it didn't hel

What should I do?

 

Not sure about the M4600 but with an e6510 I recently owned I had to update to A10 (from A02) first before I could update to the recent A15 (latest at the time). You may want to read the finer print in the BIOS update instructions on Dell's Support website just in case additional directions are stated.

 

I read about this problem and unfortunately it is a MB problem (very common).

 

Check to see if your bios states, "Signed Firmware Update is enabled" on the system information tab. There is an issue where this could be enabled without the correct signature / key. Accordingly future bioses will not match the key and therefore will not install.

Unfortunately there does not seem to be a fix beyond physically replacing the bios chip. Under warranty Dell replaces the entire motherboard.