Just did this. Steal a weapon from one of the "V-Fire" enemies nearby. Drop back down the beginning, where you started. Fire the V-Fire weapon at the wall from the other side of the snow, and it will go through. Jump down and enter the door.
Then steal the keycard in there as normal.
~Kurockbo~ "I played this game and beat it in three games."- darkmega12
Yes, you can symbolic319, but Hard mode doesn't give EX skills or Cyber-Elf upgrades. It's just you, your body chips, and your skillz. The Z-Knuckle actually becomes useful here, and Galacta/Junk Armour becomes better than it already is.