HTC One M8 does not enter recovery

[Taz Xanth]

My HTC One M8 is stuck in boot loop. I can reboot using volume up and power, then volume down on black screen. I get the options for Recovery, Factory Reset, etc. I select Recovery (so I can clear cache, etc). The picture of the little phone comes up with the red triangle and exclamation point, but that's it. No info, no options. After a minute or two, the phone will reset on it's own and back to boot loop. Any ideas?

Edit.. phone is not rooted. Official software and locked.

 

[Rukbat]

Start at Rootjunky's video:

https://www.youtube.com/watch?v=9HWj_1KHbuY

He has instructions to root, install TWRP (so you'll have a recovery) links to the ruu file, so you can reflash the ROM if you need to, etc.