I don't know if this is relevant to you or anyone else with this problem, but if you look back a day or so in this forum, another user experienced the same thing.  He cured his own problem by unplugging his Variax VDI lead.  This kind of makes sense as the Variax draws its power from the HD500 and therefore in his case at least, the guitar appears to have perhaps been drawing too much current/voltage to allow the HD500 to boot properly.  Once booted the Variax could be reconnected.   My initial thought is that perhaps the problem lies in the PSU rather than the HD500 itself.  I sometimes see similar behaviour with computers that are three or four years old and the internal PSU is on the way out.  A replacement PSU invariably cures the problem

I have seen my own Variax 700 prevent my X3 Live from booting now I come to remember and that was definitely a PSU issue and a lack of current - I did something really stupid to cause it: I was using my Digitech Harmony Man which has a 9v AC PSU also, but it only supplies something like 800mA and I simply mixed the two PSU cable ends up so no damage caused but the X3L needs the full 2000mA when a Variax is connected.  Had I left it that way, the Digitech PSU would have overheated and burned out and maybe burned the house down too :-(

I haven't experienced the issue myself, but if I do I have a spare third party PSU which outputs 9v DC at up to 4A and this may prove or disprove the power supply as a possible cause

I believe Line 6 are aware of this issue as I see from other threads.

Tech support are not the design, software or hardware engineers.  Their role is to support end users, resolve issues that can be resolved and where they can't immediately they need to try and reliably reproduce the issue based on the varied information supplied by end users.  Once the problem has been verified, then a bug report can be submitted by Tech Support to the engineering team team for review and inclusion in a program of bug fixes.  Tech Support can request that the bug is looked at and fixed urgently, but the final decision rests with the engineers.

Rowbi's outline of how the technical support guys see active threads is exactly 100% right, so it's important that if the original poster's question has not been answered, then the original poster needs to reply to the thread which then shows the question as still unanswered.  Sometimes users don't come back within 48 hours and at that point the thread might be closed as answered or assumed answered by Tech Support

There do seem to be a few of you with this problem or something like it.  The cause may or may not be the same in all cases.  I suspect that there may be more than one root cause and  whilst in itself identifying the causes doesn't necessarily immediately resolve the issue for users that are affected - (an exchange unit satisfies that immediate issue) the causes still need to be identified.

The numbers of users with this or similar issues does seem to be very small given the reports here against the numbers of units that must have been sold since 30 September.  There may be one or two other users who have experienced similar and not reported it here.   I wouldn't expect this apparent common issue to be very widespread to be honest, so if a unit develops this fault and is replaced I think it quite unlikely that users would see a repeat  performance.  However, that said it is important to find out what's actually causing the problem(s).

Nick

With all due respect, if you believe it's sporadic or not, Line 6 have not responded to anyone with this problem and in fact marked topics with this problem as answered. That's unacceptable. I work for a major retail companny and if six people returned the same item with the same problem, we would launch an investigation. Certainly wouldn't pretend it's a one off.