[One (M7) Q&A, Help & Troubleshooting] skypse:
So, I took a look around the forums thinking that maybe another newbie such myself did this thing but apparently I am one of a kind. So here is my story:

I have my HTC One M7 since the summer of 2014, I rooted it without any problems and unrooted it when the Lollipop update came out. After two or three days of the update, I had a problem where my phone would lose all sounds and would be unable to play any media that involved music. I thought it might be a software problem so I rooted it again and I installed the ViperOne ROM from the forums. Despite the fact that I really loved the ROM, the problem insisted and once/twice a day I needed to clear cache, restart the phone and if I was lucky it would go away on the first trial.

P.S. The problem only occurred when a call started.

This past Friday however, the problem wouldn't go away no matter what I did. My phone had lost all sounds and I couldn't do anything about it. Ringtones, alarms, videos, youtube, calls, even the bootup sound, nothing.

So I decided to redo everything from the beginning, in case I did something wrong and with the hope that it will just get fixed. Thinking that my software was the problem, I decided not to do a backup (please don't kill me I know it was a stupid decision) and to just wipe everything off, and do it from scratch. I re-installed viper as a first step but it didn't fix. I wiped the whole system and data partitions and installed the ROM again, nothing. Then I tried to install a clean HTC RUU and I found that the latest was this one

RUU_M7_UL_K44_SENSE55_MR_BrightstarUS_WWE_4.19.1540.9_Radio_4A.23.3263.28_10.38r.1157.04L_release_353887_signed_3

but it needed to be installed through HTC Sync and it just wouldn't work. I was getting a message that the phone was not connected.

Uninstalled HTC Sync, Re-installed HTCDriver_4.1.0.001 and downloaded a KitKat ROM from HTC1Guru site but when I tried to install it, I was getting an error message from the TWRP recovery.

Next, I downloaded Guru_Reset_M7_2.24.401.8, installed it, opened it, sound still wouldn't work no matter what. Also, while I installed the Guru Reset, I was asked if I wanted to also install stock recovery and I said yes. Since this ROM was able to be installed, I started doing the OTA updates with the hope that one of them might fix the sound problem. On the third update, the phone got bricked and stuck in a bootloop.

At this point, I can only enter bootloader without the phone crashing.

Recovery gives me a Red triangle with an exclamation mark in it.

Factory Reset goes bootloop.

And the worst of all is that now my PC doesn't recognize the device and fastboot commands give me the "waiting for device" middle finger and I can't do anything.

TL;DR

phone got bricked and stuck in a bootloop.

At this point, I can only enter bootloader without the phone crashing.

Recovery gives me a Red triangle with an exclamation mark in it.

Factory Reset goes bootloop.

And the worst of all is that now my PC doesn't recognize the device and fastboot commands give me the "waiting for device" middle finger and I can't do anything.

Please help me I don't know what to do and I cannot send it to service to fix it because the Bootloader has the "Tampered" message on top.

This is what my bootloader has:

*** TAMPERED ***

*** UNLOCKED ***

M7_UL PVT SHIP S-ON RH

HBOOT-1.61.0000

RADIO-4A.17.3250.14

OpenDSP-v35.120.274.0718

OS-7.19.401.2

eMMC-boot 2048MB