the next step is to open a case with apple and ask for a repair or replacement. you can then ship the device back to apple and they will refund your shipping. this is the process that apple is most likely to take.
ast 2 is able to diagnose both macs and apple tvs. theres nothing really to say about how well it does this; ive never actually used it. if your macs can be configured to a diagnostics screen, you can use ast 2 to make a diagnosis. if your apple tv is installed with an apple id, you can make a diagnosis using ast 2 as well. apple tv's run on os 9, so youll have to run ast 2 using the os 9 version of ast 2 (not ast 1.4).
you can only access ast 2 with an active connection to the web, and an authorized account with apples private global services exchange, or gsx. with an account, and certifications installed on your macbook or ipad, you can then service apple devices. you need a devices serial number, which can be either read off the device in front of you or given to you over the phone. this remote connectivity is how apple store employees can check devices on the store floor, without lugging around cables or computers.
it still makes me smile when i again here the merits of using a mac as the studio computer of choice - but all (especially tdm) recording systems had an external bank of processors that did all the it grunt (the actually running of the processor components like live recording, virtual plugins etc.) - the g5/macbook was basically a pretty screen running just the graphics. now we have intel i7s multi-core processors and internal ssds which do perform everything. apparently apple senior management and nvidia (who made the graphics cards) had come up with a great way to lever even more profit by reducing the solder by 50% on the gpu. if the mac got too hot it started to melt the small amount of solder, causing the gpus to fail. a 300 repair job each when mine failed in both my macbook pro and imac 3d9ccd7d82