The 757 alternate gear extension utilizes hydraulic power to release the uplocks which allows the gear to free fall. The 767 utilizes a small electric motor to release the uplocks. The LOT 767 gear up landing was due to a popped circuit breaker which also powered the small electric motor that released the uplocks which then allowed the alternate gear extension to work. 2 different systems, so an electrical issue shouldn’t affect the 757 alternate gear extension system. This will be an interesting investigation.
We had a similar scenario in the C-141, where a crew due to limited fuel, rushed the alternate gear extension checklist and failed to secure the nose gear. It collapsed upon landing.