Yep, the cable snapped.
When I purchased my vehicle this spring, I noticed it was hard to open the hood. After inspection, the front cables started to fray, had the plastic sheathing broken, and were rusted. Replaced them, and opening the hood went buttery smooth.
To change the cable is actually very easy, but the issue you have is opening the hood without breaking the grill.
Here is a solution how to open the hood without breaking the grill. It's for e39, but the mechanism is the same (I have an e39 as well). The only difference is that the opening lever on the e39 is on the passenger side, and the x5 is on the driver's side.
Here is a linky how to prevent premature breaking of the hood release mechanism - again for e39, but very similar with e53.
Here is a linky how to replace the cable (guideline - it's e39) - but on the e53 is much easier, you don't have to remove anything except for the plastic cover of the air intake & radiator cover, then snake in the middle cable above the left headlight to join the front cable.