So I tried to sideload Clockworkmod via USB but ADB doesn't seem to recognize the phone in Windows 8. I installed the official HTC package, but the device doesn't show up when I use 'adb devices', so I can't sideload anything (phone was connected to a USB 2.0 port on the rear panel). I tried the same thing on my MacBook Retina with Windows 7 on Bootcamp, same problem. I read there might be problems with USB3 but my MacBook doesn't have USB2 ports any more. I havent tried getting into my phone in OSX or Linux yet since I couldn't find a decent guide, I only know a few basics with the Unix terminal.
Can anyone give me any tip how to get my phone to work again? I also have a USB OTG Adapter, maybe that helps?
Here is a video of my phone with the Clockworkmod Logo bootcycle (can't post links yet so please copy-paste it).