Help HTC One - blackscreen

[Stopak]

Hello, I've a problem with my HTC One.
It has been working really fine until now.
Suddenly my screen was black and the 2 software buttons "turned on" (they're permanently lighted now, no flashing).
(I dont know if this has somthing to do with problem but i have to tell it anyway... It happened when i tried to connect my device to my TV via 3.5mm Jack audio cable and then i was switching sources on TV)

I tried to find some solution for this problem but all threads about this problem is with flashing SW buttons and its solved by holding power button or volume down button. This apparently doesn't work with my phone.

When I connect it via USB to my PC, nothing happens, neither LED notification doesn't work when i connect my charger.

I'd appreciate if you could try to help me with finding solution for my problem.
Thank you.

 

[Hadron]

Holding the power button down for an extended period (up to 20 seconds) should force a restart more-or-less no matter what. If it doesn't, make sure you do it in a brightly-lit environment with the light/proximity sensors uncovered: some owners have reported it not working if there is not enough light, presumably a protection against the phone being restarted in a pocket.

If it still won't, then I'm not sure what the options are. The charger light not coming on is not encouraging. Just to check: is the phone rooted, and is USB debugging switched on? If you don't know, then the answer is almost certainly "no" (occasionally people buy second-hand devices and don't know that these things have been done, but that is unusual).

 

[Stopak]

Thanks for reply.
Unfortunately holding power button doesn't work even if its done with flashlight shining right to the sensors.
I bought this phone as brand new and its NOT rooted. And because of that I think that USB debugging is not switched on (i didnt change any settings, so if factory new phone is defautly set to "usb debugging off", it isn't ON now).

 

[Hadron]

No, you would have to jump through some hoops to turn usb debugging on - it won't happen by accident. That's a shame, because if we could get it to respond to ADB we could force a restart (or recover data). Though to be fair I'd be surprised if it responded in the state it's in.

I find it hard to believe that the headphone socket being connected to the TV could cause serious damage. But right now I'm not coming up with anything better than "hope once it runs out and shuts down it will respond to the charger" .

 

[marctronixx]

the physical headphone port may be damage so much so that it's causing issue elsewhere on the device.

instead of chasing ones tail over the internet, taking it into a service depot may be the best option here. not being able to diagnose over the Internet makes it difficult to find a solution.