You need to make a brake line for each reservoir exiting port that loops back into the reservoir.
Then pump the brake pedal a couple of times or at least until air bubbles stop coming out of the tubes.
Then reconnect the lines to the front and rear brakes and bleed them as usual.
You bleed the longest line first.
On most cars that is the right side of the car.
If the pedal does not come up now, that means the master is not producing pressure and it is leaking internally and as such should be considered defective.
That is happening more these days since quality control has gone out the window. Products are being built "off shore", which is a generic term for "good luck pal".
