Unable to start the lab

I could complete the assignment and when I tried to submit , I got the 403 error. On restarting the lab and submitting again, I got a score of 0/100 even though all the code cells ran successfully. Not sure what to do now.

I could finally submit the assignement. Looks like all the cells ran successfully with desired results but that is not reflected in the scores. I would appreciate if anyone from grading team can look at the submission and let me know what went wrong.