This happened to me as well and here are my observations and the fixed.
1. Frunk failed to open due to ice build up.
2. Did not do any attempt to open it again but just continued to drive. After about 30 min while driving on the highway, suddenly the message "frunk is open" popped up. And a few minutes later, the car limited my speed to about 20Km/Hr, luckily I already exited the highway.
3. After I stopped and without even getting off the car, I just open the frunk from the screen (it opened all the way this time) then closed the frunk again. (Success!!!)
4. Another freezing cold event (-10 C). I open the frunk and didn't open. I pulled the emergency release cable this time and still couldn't open. Tried several times but still couldn't open.
5. Drove for about an hour and no frunk warning.
6. The next day, I poured warm water around the hood, especially around the latch area, suddenly the frunk popped a little bit by about 1/2 of an each.
7. I opened the frunk again but still failed. Then tried again but this time I grabbed the edge of the hood close to the latch. As soon as I heard the solenoid pulled the latch, I helped the hood to move up and it opened. Success!!
8. But now, the frunk doesn't close. The latch is not engaging properly.
9. I removed the plastic latch cover to check the latch mechanism. The emergency release cable was preventing the latch spring to move freely.
10. After I removed the emergency release cable from the latch mechanism, I can now open and close the frunk again without any issues.
11. My conclusion, it was the emergency release cable that jammed the latch mechanism. Needs to be redesign.
12. In winter times, if the frunk failed to open, do not try to pull the emergency release cable. Just drive around or pour warm water or anything that could melt the ice to break the bond.
13. And yes, I will still keep my power frunk.