TL;DR summary: Pair an X1 remote with the Arris X1 DVR/STB with SETUP-987. Diagnostic mode is EXIT-DOWN-DOWN-2.
Now, the whole rant.
Comcast is in the process of imposing its X1 set-top box platform on its subscriber base, like it or not. Starting last March, our older Motorola STBs started interrupting our programming daily to display a warning that we probably had to replace the box soon or we'd lose access to channels. We were to tune it to a certain special channel which would test the box. And indeed our older boxes failed, though a more recent replacement box said it would still be okay.
I inquired about the reason for the change, and someone admitted that it was because they planned to switch some HD channels from MPEG-2 to MPEG-4. That newer encoding format needs less than half the bit rate of MPEG-2. It's been around for, oh, 17 years or so -- its original patent pool rules were so draconian that hardly anyone used it. The DTV transition standards adopted MPEG-2 instead of MPEG-4, doubling the required spectrum, because of the patent terms. Now that some of its key patents are apparently up, the king of the cheapskates, Comcast, can use it.
But over a month after the supposed drop dead date, they are still using MPEG-2. You can tell from an X1 box if you put it in diagnostic mode. One screen shows you what frequency the six tuners are on. Another shows you which MPEG format they're using. It's always MPEG-2.
To put the unit into diagnostic mode, using the new black X1 remote, hold down EXIT for a few seconds, then press DOWN DOWN 2 . It's got useful information. EXIT puts you back into normal mode.
But that points to another problem with the remote. The X1 box has only one button on it, a power button, which the remote doesn't even control. You leave it on all the time, and the blue light has (if you look hard enough) three brightness settings, which I'd call bright, brighter, and brightest. Great for the bedroom TV, not, if you leave the light enabled at all.
The box has no control buttons. It depends entirely on the remote. The old Motorola DCT did have channel buttons, though you rarely used them. They were nice for emergencies, like a failed remote. But the old remote ran for a long time. The X1 remote, however, has backlighting, so you can see the buttons at night. Which is nice, but it turns on based on an accellerometer: When the remote is moved, the lights come on. This does wonders for battery life, especially if you have a bedroom TV and leave the remote on the bed. You are lucky to get two months from a set of AAs. And without the remote, no TV. Like so much of Comcast these days, it's a bunch of half-baked maybe originally decent ideas that are badly executed.
Comcast these days reminds me of the old Chrysler Corporation. It had teams that went around the company demanding that product costs be reduced by a certain sum. Take $12 out of the cost of the Volare or be fired! Senior management assumed that cutting costs by $12 meant $12 of higher profits. But the result was badly made cars that potential customers learned not to buy. They saved their way into bankruptcy. Comcast has a monopoly in most areas so it doesn't have to worry about losing so many customers.
Which brings up the second secret of the X1. The remote can control your TV set too, which is nice. So it has a setup function. But what they don't tell you is that the same control also works with their older boxes. So if you still have an old Motorola box (they admit it still works okay on a non-HD set) and want a new remote, you get an X1 remote with instructions to use SETUP-B. A Cisco box is SETUP-C. But X1 customers aren't told how to pair it with an X1. It comes that way, but if you bump into the SETUP button (grab the control backwards and it's easy) it can un-pair with X1. And remember, there are no buttons on the box itself.
This happened to me, so I tried to call for help. Their auto-attendant jail now tries to use voice recognition instead of touch-tone, which is an awful idea, and asks you for all sorts of account ID before you can reach anyone. Then you have to listen to a commercial! for a dumb pay-per-view rasslin' match. Then it transfers you to the wrong department. If they manage to transfer you to tech support, you won't get any unless you go through the third degree security grilling again: They don't get the validation you already gave them, EVEN IF YOU ARE CALLING ON A COMCAST LINE. It seems to be that their "technical service" low-paid agents have a script that won't give them access to any technical documentation until they've gone through a massive security script designed to prevent the billing from being changed or CPNI from being released to the wrong person. Even if you just want to ask a generic question. It's a pathetic mess.
Eventually, though I did find out the answer, from a supervisor.
To pair an X1 remote with the Arris X1 DVR cable box, SETUP-987 .
Note that you have to hold down SETUP until it turns green, though it does seem to accidentally lose settings more easily. Then you enter the number. This is NOT in the X1 documentation provided to customers. But you will need it if you have an X1 box.