They've sent me an RMA too and offered to pay for postage; like you though, I'll end up potentially having no radio while they fiddle and piss around for a few days. I don't think the radio works properly (or even at all) without the canbus box either. If it works partially, I can live without it, but I really don't want to be driving around for a week while they fanny about sourcing a new canbus decoder for me. I'd need to look though which I'll do tonight or early tomorrow morning. I'll update once I know. If it does work, I will get it posted tomorrow so I can get a new one back next week. I wouldn't be surprised if it doesn't fix it though.
The 30 second ACC fix should work, assuming your canbus hasn't bugged out already!! It's really really important to note that. Once you've bugged your CANBUS, it's done. Dead..... and it'll be dead for half an hour to an hour or so regardless of this setting. I'm not uber clued up on the car, but I found an article discussing BMW canbus and aftermarket radios and essentially, there's some kind of lockdown system. If any kind of discrepancy is detected, the canbus circuitry for the radio is shutdown. So with that in mind, I think the car detects the unit powering down, but the unit should be powering up as the door has just been opened. This then puts the car into a fail-safe and canbus into a shutdown mode. You could disconnect the battery for a quick answer, I suppose, but no point. Just wait an hour or so. Then you'll have working canbus everytime you enter the vehicle, assuming you have that 30 second mode activated.
This isn't a fix though is it? This is simply booting the radio from cold everytime you enter the car and that really shouldn't be necessary. It was one of the selling points of this particular piece of equipment.
I will try those settings tonight/tomorrow before sending it back. Has to be worth a try.