laptop with no battery and no screen

[My Name]

Hi, I'm trying to install 12.04 on a laptop using an external monitor and without a battery. it's an aspire 5335 laptop body only. I'm getting a problem with it not installing because it is getting an error when checking for a battery. I have tried to boot with acpi=off which has no effect. I have also tried to boot nomodeset but this gets a scrambled screen, but does seem to boot.
Any ideas what i can do to get this installed?