When you say starts/stops (etc) are you saying it just keeps trying to reboot? Or are you getting a message such as boot disk not found press any key to restart? Replacing the 3V battery will cause the CMOS to reset to factory defaults. You may need to go into the CMOS and make setting changes to point to the proper disk drive for booting. You may even have to change the type of disc drive since there is now the old MBR as well as the newer GPT format. Also, there is the possibility that if you are upgrading you may need to use the legacy CMOS instead of the UEFI that many newer mainboards come defaulted to. Any error in the CMOS settings can cause a boot failure.
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When you say starts/stops (etc) are you saying it just keeps trying to reboot? Or are you getting a message such as boot disk not found press any key to restart? Replacing the 3V battery will cause the CMOS to reset to factory defaults. You may need to go into the CMOS and make setting changes to point to the proper disk drive for booting. You may even have to change the type of disc drive since there is now the old MBR as well as the newer GPT format. Also, there is the possibility that if you are upgrading you may need to use the legacy CMOS instead of the UEFI that many newer mainboards come defaulted to. Any error in the CMOS settings can cause a boot failure.