Precision M4800 BIOS reset / password removal

I have a Dell Precision M4800 that we used for a project several years ago and typically noone documented the bios password which was set.

I've tried removing the CMOS battery and discharging all power but that doesnt seem to do the trick.

I've also tried a couple of sites which claim to offer dell master passwords but neither seems to work.

Does anyone have any ideas or recommendations on how I can reset the BIOS on Dell Precision M4800 laptops?

I don't really want to have to call Dell Support because well, its a painful experience, and the laptop was supplied by a partner from the project so we wont have it on our Dell account so getting them to support it will be difficult.

#sigh

Any advice gratefully received!