Lego Fiber Optic
1996
Given the success of its brand, movies, and theme parks, it’s hard to believe that twenty years ago Lego was struggling. The toy giant replaced experienced toy designers with younger ones, who failed to consider production costs. One example is Lego Technic Fiber Optic, which ended up costing Lego more to produce than what the set sold for. The numbers just didn’t stack up.
Additional info:
The Guardian - How Lego reinvented itself
Businessinsider.com - Disastrous Lego kits ruined the company
This talk by David Robertson who was LEGO Professor of Innovation. It's a long video, and might only appeal to innovation nerds: