Trying to install El Capitan, kernel panic

Hello!

I have been trying two different methods for installing El Capitan with the same result.

1. Upgrading from Mountain Lion.

2. Fresh install on a new SSD from a bootable SD-card.

I don't know how to copy the text during the kernel panic so I took a photo of what it looks like. They are slightly different.
The only known issue with the computer (MBP9.2, 13", I7 2.9 GHz) is the:

"To prevent damaging your computer, the USB device drawing too much power has been disabled. Other devices may have also been disabled. When you disconnect the device drawing too much power, your other USB devices will be enabled again."

Which pops up from time to time. AHT says "No trouble found". Both SMC and NVRAM have been reset.

I've managed to restore the computer to Mountain Lion for now but would prefer to upgrade.