I had the best of luck with the step-by-step here:
At this point all I want is XBMC so I don’t want to bother registering and paying for aTV Flash. So:
Apple-TV:~ root# echo "deb http://mirrors.xbmc.org/apt/atv2 ./" > /etc/apt/sources.list.d/xbmc.list Apple-TV:~ root# apt-get update Get:1 http://apt.modmyi.com stable Release.gpg [189B] Get:2 http://nitosoft.com Release.gpg [487B] Get:3 http://cydia.zodttd.com stable Release.gpg [189B] Get:4 http://nitosoft.com Release [277B] Get:5 http://apt.modmyi.com stable Release [1328B] Get:6 http://cydia.zodttd.com stable Release [1619B] Ign http://mirrors.xbmc.org ./ Release.gpg Get:7 http://nitosoft.com Packages [3438B] Get:8 http://apt.modmyi.com stable/main Packages [1573kB] Ign http://mirrors.xbmc.org ./ Release Get:9 http://cydia.zodttd.com stable/main Packages [1619kB] Get:10 http://mirrors.xbmc.org ./ Packages [502B] Get:11 http://apt.awkwardtv.org stable Release.gpg [198B] Get:12 http://apt.saurik.com tangelo-3.7 Release.gpg [189B] Get:13 http://apt.awkwardtv.org stable Release [1033B] Get:14 http://apt.saurik.com tangelo-3.7 Release [639B] Get:15 http://apt.thebigboss.org stable Release.gpg [197B] Get:16 http://apt.thebigboss.org stable Release [677B] Get:17 http://apt.saurik.com tangelo-3.7/main Packages [22.9kB] Get:18 http://apt.awkwardtv.org stable/main Packages [6543B] Get:19 http://apt.thebigboss.org stable/main Packages [790kB] Fetched 4022kB in 17s (230kB/s) Reading package lists... Done Apple-TV:~ root# apt-get install org.xbmc.xbmc-atv2 Reading package lists... Done Building dependency tree... Done The following extra packages will be installed: bsdiff gawk org.xbmc.xbmc-seatbeltunlock The following NEW packages will be installed: bsdiff gawk org.xbmc.xbmc-atv2 org.xbmc.xbmc-seatbeltunlock 0 upgraded, 4 newly installed, 0 to remove and 8 not upgraded. Need to get 40.3MB of archives. After this operation, 1331kB of additional disk space will be used. Do you want to continue [Y/n]? WARNING: The following packages cannot be authenticated! org.xbmc.xbmc-seatbeltunlock org.xbmc.xbmc-atv2 Install these packages without verification [y/N]? y Get:1 http://apt.saurik.com tangelo-3.7/main bsdiff 4.3-1 [6824B] Get:2 http://mirrors.xbmc.org ./ org.xbmc.xbmc-seatbeltunlock 1.0-4 [2950B] Get:3 http://apt.saurik.com tangelo-3.7/main gawk 3.1.6-2 [424kB] Get:4 http://mirrors.xbmc.org ./ org.xbmc.xbmc-atv2 10.0-8 [39.9MB] Fetched 40.3MB in 32s (1233kB/s) Selecting previously deselected package bsdiff. (Reading database ... 1283 files and directories currently installed.) Unpacking bsdiff (from .../bsdiff_4.3-1_iphoneos-arm.deb) ... Selecting previously deselected package gawk. Unpacking gawk (from .../gawk_3.1.6-2_iphoneos-arm.deb) ... Selecting previously deselected package org.xbmc.xbmc-seatbeltunlock. Unpacking org.xbmc.xbmc-seatbeltunlock (from .../org.xbmc.xbmc-seatbeltunlock_1.0-4_iphoneos-arm.deb) ... Selecting previously deselected package org.xbmc.xbmc-atv2. Unpacking org.xbmc.xbmc-atv2 (from .../org.xbmc.xbmc-atv2_10.0-8_iphoneos-arm.deb) ... Setting up bsdiff (4.3-1) ... Setting up gawk (3.1.6-2) ... Setting up org.xbmc.xbmc-seatbeltunlock (1.0-4) ... Found ATV2 running ios 4.2+/AppleTV Frontrow app md5sum is unknown, not patching Setting up org.xbmc.xbmc-atv2 (10.0-8) ...
Started with greenp0ison and possibly got to DFU mode properly (who knows, HDMI wasn’t connected – and in fact, the particular one I have is too thick to be installed with the micro USB at the same time). DFU didn’t seem to register so searched around and found someone recommending the hacint0sh.org forums, where Seas0nPass seemed to have a good response. So went with that.
For the XBMC installation this worked for me.