I have moved this from my comment elsewhere, and suggested that it was caused by the redundant modules for tracking and so on built in to firmware and initrd . Here's a pretty good response on it from the reddit user who had the same problem.
Here's the best response I've found online regarding how to install a legacy trackpad firmware update. Note, if you are not familiar with snooping on the wireless interface, you probably should not try this. It is invasive. I followed these instructions, and could see the trackpad firmware update, but it failed to load. This was after following this.
I soon found how to fix the wireless/Bluetooth/wifi on my Dell studio 15 for Ubuntu. I then followed these instructions for installing Ubuntu on the machine. The installation went fine, and I rebooted. I found that the trackpad would still not work, and it did not show up in system/preferences/mouse or trackpad. I also could not get to a terminal using Ctrl-alt-f1. I tried everything for several hours, including duplicating the /boot/initrd.img file and rebooting. I went to the excellent Ubuntu forums and searched for the driver and firmware versions. d2c66b5586