HD2 Stuck in bootloop

If it's stuck in a bootloop, we can assume that you still have your android bootloader working. Now if you don't see Magldr's header at the top when booting up, then you have cLK, otherwise it's MAGLDR.

If you have MAGLDR, hold the end button when you see magldr's header. (Does this also take you nowhere?)
If you have cLK, boot up the device and immediately hold the back button. This should bring up cLK's interface.

From there, check that you have cwm installed. If it is installed, then just copy the same ROM and flash it again. (Or resize partitions then flash the rom if you want to install another one)

If it's not installed, just follow one of the guides available on this forum to install the recovery.

You said you've installed Android two years ago, so I'm assuming you're familiar with all of those stuff.

Good luck.