You should not need to start over. Go talk to the Raanaar in the centre room of the level, who should open the door to the room south with the stairs to the next level.
If he doesn't recognize that you have completed the third summoning test, you can bypass the locked door. Possible methods to do this include;
[*]
Teleporting anywhere (via hex editor)[*] stand by the wall and alt-tab the game a few times to see if you can shift the character position slightly and get through
[*] the trick described in
armory trick in act 1 to get a summoning doll through the wall and then use it to enter the BF and exit