Vostros does no recognize dell battery

Have TWO Vostro's (win 8.1) having a problem with one. It will not recognize either dell batteries (OEM) the good one recognizes both batteries (84% & 93%) and both Ac-Dc power supplies. The problem one will not boot with either battery or power supplies.

1. Have replaced BIOS battery 

2. Done the power drain/restart sequence

3. Cleaned both batteries and motherboard connection

4. Rebuilt MBR

5. Windows and dell drivers are up to date

6. Installed win 7 - same problem

I want to update BIOS but can not because of the battery problem,  is there a way of updating without a battery?  I do not care about using battery