Toshiba Portege R100 CMOS/BIOS PROBLEM at startup.

I am working on a Toshiba Portege R100 laptop. When I got it, the RTC battery
Was stone dead. I replaced it with a new one.
When I turn the machine on, The Toshiba screen flashes on for
1 or 2 seconds, then it goes to either one of two different screens. One screen says ( RTC battery is low or CMOS checksum is inconsistent !! ) Press F1 KEY to set DATE/TIME. If I hit F1, I go into the BIOS, but can do nothing at all in there. The other screen I get , once again, at startup, the Toshiba screen flashes on for 1 or 2 seconds, then it goes to a DOS LIKE screen, but only displays 8 or 9 characters in the upper left screen corner. Example: (A-UEVC=!!*e )
Once this DOS LIKE screen is displayed, it stays that way at every boot up. The only way I can get rid of it, is to unplug the RTC BATTERY, remove the Main battery, then start over. Then it goes to the message screen again, about going into the bios. But it only displays this ONE TIME. After that, at startup It goes right back the GIBBERISH in the upper left screen corner.
This is a new one on me. Is there a way to reset the BIOS/CMOS?
Can anyone HELP????
Thanks,
Phil