CMOS Checksum is invalid, CMOS Reset (50)

[wbouguereau]

Replaced battery and now cannot run off battery power.  Must keep laptop plugged in at all time for power.  Upon bootup getting CMOS Checksum is invalid, CMOS Reset (50).

[erico]

You will need to recover the corrupted  BIOS.

With the power adapter connected, hold down  the Windows key and the B key at the same time.

Press the power button without releasing hold down  the Windows key and the B key. 

You might have to hold the keys down for up to a full minute.

Hold those keys down until the laptop responds with a message that says BIOS recovery started and then release the keys.

Wait until there is a message that tells you the the BIOS recovery is complete.

That should return normal charging.

All of this happened because the CMOS (BIOS) chip gets the power it needs to retain the BIOS setting from the battery that you replaced.

If you used the laptop for quite some time when the original battery had failed and then replaced it, that explains the symptoms that you have reported.

After the BIOS recovery is complete you may need to reset the EC (embedded controller) chip.

"Use this procedure to reset the EC. Turn off the computer and disconnect the power cord for 5 seconds. Connect the power cord to the computer, and then press the power button to turn on the computer"

[wbouguereau]

Erico,

This does not work.  I get the login screen with the login area filled with * which are probably B's.  I never get a message saying BIOS recovery started.

What else can I do?

thanks,

mik

[erico]

As far as I am aware, the only resolution will be to replace the BIOS chip with one that has a fresh copy of the BIOS ROM.