STAY BREAK IN APPLIED POSITION

All about engine; 
The brake pedal free play are not equel. 
Due to this, piston Inside the master cylinder Not coming behind Clearly. 
Therefore, hydraulic pressure Does not decreases. And 
By, wheel cylinder brake shoe Pressure Due to not begin low.
The break is not Released.

and in this hydraulic Brake system Due to not using equel hydraulic break oil.
And due to not using correct oil Rubber cap has been Damaged.

 that is the one reason
And If the rubber cap has been damaged Then, For example if The piston coming To behind then, Due to rubber cap The Bypass port gets closed.

and For this hydraulic pressure does not decreases.

and brake stay applied position.