If you get the HTC logo on a restart then the display hardware is working. so most likely a software problem. At what point in the boot sequence does the display go black: do you get the boot animation, or just the spash screen? Any information you can give might help someone diagnose it. In fact tell us everything you can about the phone model, setup, what other mods you've made, what you were doing before the problem started, whether you use ROM Manager,...?

As this is a rooted phone you might get a better response in the root subforum (you can ask a mod to move the thread).

Most importantly, can you see the hboot screen and recovery menu if you boot into them? If you can, then that sounds like a ROM or user app/data problem. But also if you can use recovery we have many options. Simplest would be to try reflashing the ROM, see whether that helps. If it doesn't, are your app/data backups (e.g. Titanium) up to date? If they are, you could try a factory reset from recovery and see whether it boots OK - if it does, then try restoring apps but not system settings. I'd normally say take a nandroid before doing anything, but there's a good chance that such a backup would also back up the problem.

If you can't see the recovery menu then it's a bit trickier, but we still have options. If absolutely nothing else works, there's always the ROM Update Utility, which will unroot and return to stock software (and wipe your apps and data). But no need to rush - we should try to find a less destructive solution first . You should not return the phone for repair without trying the RUU, since in any event you will have no warranty if it is running custom software, but if it's a software problem the RUU should fix it anyway (though there are a few exceptions).

But also do move the thread, or start a new one in the root forum (with as much info as you can think of). I don't recognise this problem, which is why I'm just making some generic suggestions above, but there's always a chance that someone else will.

 

Has the phone been dropped?

Check this thread out: http://androidforums.com/desire-sup...sire-screen-wont-turn-after-goes-standby.html

There's been at least two people with a very similar fault caused by a capacitor (the same one in both cases) coming loose in the phone after it had been dropped.

As you're at the end of your contract, you've got little to lose stripping it down.