FP 2 + Android 6 Upd > boot freeze without option to recover

There is! → dic:recoverymode But you do it the right way anyway:

That should get you to the resting robot screen. If you are still on Android 5 (which I’d guess since you say the progress bar never got past 70%) you then only have to press the power button to open the menu. On Android 6 it would go like this:

But what you describe:

Sounds like dic:fastboot mode. (Usually you’d get there by pressing Vol- + Power

Do you have a Slim Cover?
Slim Covers are known to cause Button Issues. It’s usually the Power button, but maybe your Vol- button is stuck. If so take the cover off and then try to get to recovery again.