I am stuck in the room with the closed iron gate and two red crystals.
I use Jak's boots to jump up to the ledge and press the button. I then run over to the other button and press it. no matter how many ways I try I cannot get the iron door to open.
Ah, Freeze/sins_to_dark you might have missed it, but you need to hit the keyhole with a normal arrow first before you can equip the arrow. Didn't know that myself as I didn't try to equip it until I'd already hit the hole with a normal arrow.