If I keep the power button pressed, the capacitive buttons flash exactly 15 times and occasionally the phone vibrates. I don't have a One S so not sure if that indicates that phone was started or shutdown.
Neither fastboot devices not adb devices shows the device. But every once in a while when it vibrates, if the phone is connected to the PC with a USB cable, it beeps - like it's connected. I don't see Android Phone in Device Manager. But I see a MTP USB Device with a yellow exclamation mark. Uninstalling and reinstalling HTC Drivers didn't fix the problem.
I have tried Power+Volume Down key. Shining a torch on it (seemed to work for a few people), keeping it plugged into the mains for 3 days, kept it in the freezer for 2-3 minutes (also seemed to work for one person).
I think when I first got the phone and plugged it into the mains, I saw a red charging light. But I may be mistaken. In any case, there is no light anymore indicating charging. But I don't think that's the problem.
I have no idea whether the device is bricked or not. And if there is any way to fix it. Samsung has Odin which makes any Samsung phone practically unbrickable. I haven't used any HTCs since the G1 so have not been in touch too much with the HTC development. But from reading, it seems that messing around with Romming with S-ON can cause the phone to be bricked. And perhaps that's what my friend or his friend did. Does this sound like that's what could have happened?
Thanks for any pointers.