Not sure if you can actually downgrade via safe mode, I think you need to do it through neighbourhoodif i'm not mistaken, testkits are able to downgrade, so try updating with a lower leaked fw
UPDATE: this should work, its a 1.76 testkit fw
https://mega.nz/#!sVgU0BSY!GZ-60JnKgMiyZMJaGbcLzY4FNzPCagQOyRntTYXT8uA