I agree with kevin. Your initial problem was most likely a failed wheel cylinder. Now it may be harder to identify which one is leaking due to the runoff from the bleeding operations (unless you caught it all in a container).
The key would have been whether your brake master cylinder reservoir was emptying itself (fluid level low) or not when the brakes suddenly went south.
If you lost brakes and the fluid level in reservoir was not dropping, then yes.......could be a defective master cylinder.
If you lost brakes accompanied by a loss of fluid from the reservoir without an obvious leak, then I would have to say look for a leaking wheel cylinder.
Typically if the reservoir loses fluid from the brake master cylinder it will show up as a leak where the brake pushrod enters the master cylinder, or you will see where the brake pushrod has grown a "beard" from collecting dust and lint trapped in the leaking fluid.