Debian installation can be a hassle when new hardware with non-free firmware support is necessary. A typical workaround is to use a Debian install image which includes non-free drivers.
Typically, such an ISO CD image is located under here.
Choose the installation you need (for now, it is amd64 Jessie RC1), and download an ISO image:
$ wget http://cdimage.debian.org/cdimage/unofficial/non-free/cd-including-firmware/weekly-builds/amd64/iso-cd/firmware-testing-amd64-netinst.iso
Find a USB stick (which you do not mind formatting entirely; all existing contents on the still will be wiped out with this method), connect it to a working box, and find the device pointer to the stick:
$ sudo fdisk -l ... Disk /dev/sdb: 16.0 GB, 16008609792 bytes 255 heads, 63 sectors/track, 1946 cylinders, total 31266816 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xb745c02d Device Boot Start End Blocks Id System /dev/sdb1 32 31266815 15633392 c W95 FAT32 (LBA)
We see that the USB stick is attached at /dev/sdb in this case.
Then create a bootable installation stick:
$ sudo dd if=firmware-testing-amd64-netinst.iso of=/dev/sdb bs=4M $ sudo sync