Why isn't my player/tile collision working?
From looking at usages, collidelist and collidelistall seem to take two parameters: a Rect and a list. collidelist returns the first index in the list which the Rect collides with, or -1 if there are no collisions. collidelistall returns a list of all the Rects which collided. So the line
elif player != pygame.Rect.collidelistall(cell_rects):
should instead be
elif pygame.Rect.collidelist(player, cell_rects) == -1: