[Eljaro]

Rhams, you should check your rod moving the piston inside the master cylinder. If you position it wrong you lock the brakes (like you experienced already) or you could be pumping the brake fluid back into the reservoir instead of into the brake calipers. I had a similar problem when bleeding my clutch circuit.
In the brake rest position the rod must not be adjusted to hit the inner stop in the master cylinder, but needs a little preload.