Updating Inspiron N5110 without charger

How do you update the BIOS on an Inspiron N5110 without a charger?  I have downloaded the installer N5110A11.EXE from Dell, and run it from an elevated command prompt using the line

N5110A11.EXE /forceit

but each time I do so a message box appears with the text "Error: unknown command".
  Is there a different command syntax that works with this BIOS installer?

Background

I have an Inspiron N5110 that is not charging the battery and will not run off the charger.  I have tried several chargers that work with other Inspirons.  I have replaced the power jack board, and that did not fix the problem.  Reflashing the BIOS seems to be the only remaining approach to take.

Note that the laptop is running Windows 7.